KR20230031360A - Manufacturing method of optically anisotropic layer - Google Patents

Abstract

The present invention provides a simple method for producing an optically anisotropic layer in which the orientation state of the liquid crystal compound is fixed and a plurality of regions having different orientation states of the liquid crystal compound are formed along the thickness direction. The method for producing an optically anisotropic layer of the present invention includes step 1 of forming a composition layer containing a liquid crystal compound having a polymerizable group, and step 2 of subjecting the composition layer to heat treatment to orient the liquid crystal compound in the composition layer. , After Step 2, Step 3 in which the composition layer is irradiated with light for 50 seconds or less and at 300 mJ/cm ² or less under the condition of an oxygen concentration of 1% by volume or more, and after Step 3, the composition layer is irradiated with light Step 4 of performing heat treatment at a higher temperature, and Step 5 of forming an optically anisotropic layer having a plurality of regions in which the alignment states of the liquid crystal compounds are different along the thickness direction by subjecting the composition layer to a curing treatment after Step 4 have

Description

Manufacturing method of optically anisotropic layer

The present invention relates to a method for producing an optically anisotropic layer.

BACKGROUND OF THE INVENTION A retardation layer (optically anisotropic layer) having refractive index anisotropy is applied to various applications, such as an antireflection film for a display device and an optical compensation film for a liquid crystal display device.

As the optically anisotropic layer, as described in Patent Literature 1, a laminated optically anisotropic layer composed of a plurality of layers is disclosed.

Japanese Patent Publication No. 5960743

Conventionally, when manufacturing an optically anisotropic layer as described in Patent Document 1, since the optically anisotropic layer to be laminated is formed by application for each layer, productivity is low and the cost is high.

In addition, when the coating is repeated, aggregation of the coating liquid occurs, and the desired optically anisotropic layer cannot be formed in some cases.

In view of the above situation, an object of the present invention is to provide a simple method for producing an optically anisotropic layer having a plurality of regions in which the orientation state of the liquid crystal compound is fixed and the orientation state of the liquid crystal compound is different along the thickness direction.

MEANS TO SOLVE THE PROBLEM The present inventors discovered that the said subject was solvable by the following structures as a result of earnestly examining the problem of the prior art.

(1) Step 1 of forming a composition layer containing a liquid crystal compound having a polymerizable group;

Step 2 of subjecting the composition layer to heat treatment to orient the liquid crystal compound in the composition layer;

After Step 2, Step 3 of irradiating the composition layer with light for 50 seconds or less and at 300 mJ/cm ² or less under conditions of an oxygen concentration of 1% by volume or more;

After step 3, step 4 of subjecting the composition layer to a heat treatment at a temperature higher than that at the time of light irradiation;

After step 4, the composition layer is subjected to a curing treatment to form an optically anisotropic layer having a plurality of regions in which the alignment states of liquid crystal compounds are different along the thickness direction. A method for producing an optically anisotropic layer.

(2) the composition layer contains a photosensitive material selected from the group consisting of a photopolymerization initiator and a photosensitizer;

The method for producing an optically anisotropic layer according to (1), wherein the molar extinction coefficient of the photosensitive material at the wavelength of light irradiation in Step 3 is 5000 L/(mol·cm) or less.

(3) the composition layer contains a chiral agent;

The method for producing an optically anisotropic layer according to (1) or (2), wherein the chiral agent includes a photosensitive chiral agent whose helical induction force changes upon light irradiation.

(4) The method for producing an optically anisotropic layer according to (3), wherein the total content of chiral agents relative to the total mass of the liquid crystal compound is 5.0% by mass or less.

(5) The method for producing an optically anisotropic layer according to (3), wherein the total content of chiral agents with respect to the total mass of the liquid crystal compound is more than 5.0% by mass.

(6) The method for producing an optically anisotropic layer according to (1) or (2), wherein the composition layer contains a photosensitive compound whose polarity changes upon irradiation with light.

(7) The method for producing an optically anisotropic layer according to (6), wherein the photosensitive compound is a photosensitive compound that becomes hydrophilic upon irradiation with light.

(8) The method for producing an optically anisotropic layer according to (1) or (2), wherein the temperature of the heat treatment in step 4 is equal to or higher than the temperature at which the liquid crystal compound becomes isotropic.

ADVANTAGE OF THE INVENTION According to this invention, the orientation state of a liquid crystal compound is fixed and the simple manufacturing method of the optically anisotropic layer which has a plurality of regions with different orientation states of a liquid crystal compound along the thickness direction can be provided.

1 is a cross-sectional view of a composition layer for explaining an example of step 1A of a first embodiment of a method for producing an optically anisotropic layer of the present invention.
Fig. 2 is a cross-sectional view of a composition layer for explaining an example of step 3A of the first embodiment of the optically anisotropic layer manufacturing method of the present invention.
Fig. 3 is a cross-sectional view of a composition layer for explaining an example in the case where step 4A of the first embodiment of the method for producing an optically anisotropic layer of the present invention is performed.
Figure 4 shows the relationship between helical twisting power (HTP: Helical Twisting Power) (μm ^-1 ) × concentration (mass %) and light irradiation amount (mJ/cm ² ) for each of chiral agent A and chiral agent B. It is a schematic diagram of the plotted graph.
5 is a schematic diagram of a graph plotting the relationship between the weighted average helix induction force (μm ^-1 ) and the amount of light irradiation (mJ/cm ² ) in a system in which chiral agent A and chiral agent B are used together. .
Fig. 6 is a cross-sectional view of a composition layer for explaining another example of Step 1A of the first embodiment of the optically anisotropic layer manufacturing method of the present invention.
Fig. 7 is a cross-sectional view of a composition layer for explaining another example in the case where step 4A of the first embodiment of the method for producing an optically anisotropic layer of the present invention is performed.
Fig. 8 is a cross-sectional view of a composition layer for explaining an example of Step 3B of the second embodiment of the method for producing an optically anisotropic layer of the present invention.
Fig. 9 is a cross-sectional view of a composition layer for explaining an example of step 4B of the second embodiment of the optically anisotropic layer manufacturing method of the present invention.
10 is a schematic diagram of a graph plotting the relationship between the spiral induction force (μm ^-1 ) and the light irradiation amount (mJ/cm ² ) for chiral agent A.
Fig. 11 is a cross-sectional view of a composition layer for explaining an example of Step 3C of the third embodiment of the method for producing an optically anisotropic layer of the present invention.
Fig. 12 is a cross-sectional view of a composition layer for explaining an example of Step 4C of the third embodiment of the method for producing an optically anisotropic layer of the present invention.
Fig. 13 is a cross-sectional view of a composition layer for explaining an example of step 3D of a fourth embodiment of the manufacturing method of an optically anisotropic layer of the present invention.
Fig. 14 is a cross-sectional view of a composition layer for explaining an example of step 4D of the fourth embodiment of the manufacturing method of an optically anisotropic layer of the present invention.
15 is a cross-sectional view showing one embodiment of the laminate of the present invention.
Fig. 16 is a cross-sectional view showing an embodiment of an optically anisotropic layer with a polarizer according to the present invention.

Hereinafter, the present invention will be described in detail. In addition, the numerical range expressed using "-" in this specification means the range which includes the numerical value described before and after "-" as a lower limit and an upper limit. First, terms used in this specification will be described.

The slow axis is defined at 550 nm unless otherwise specified.

In the present invention, Re(λ) and Rth(λ) respectively represent in-plane retardation and thickness direction retardation at wavelength λ. When there is no special description, the wavelength λ is 550 nm.

In the present invention, Re(λ) and Rth(λ) are values measured with a wavelength λ in AxoScan (manufactured by Axometrics). By inputting the average refractive index ((nx + ny + nz) / 3) and the film thickness (d (μm)) with AxoScan,

Slow axis direction (°)

Re(λ)=R0(λ)

Rth(λ)=((nx+ny)/2-nz)×d

is calculated

Also, R0(λ) is expressed as a numerical value calculated by AxoScan, but means Re(λ).

In this specification, the refractive indices nx, ny, and nz are measured using an Abbe refractometer (NAR-4T, manufactured by Atago Co., Ltd.) and using a sodium lamp (λ = 589 nm) as a light source. In the case of measuring the wavelength dependence, it can be measured with a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.) in combination with an interference filter.

In addition, values from the polymer handbook (JOHN WILEY & SONS, INC) and catalogs of various optical films can be used. The values of the average refractive index of the main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).

The term “light” in the present specification means active light or radiation, and includes, for example, a bright line spectrum of a mercury lamp, far ultraviolet rays represented by an excimer laser, extreme ultraviolet rays (EUV light: Extreme Ultraviolet), X-rays, ultraviolet rays, and electron beams (EB: Electron Beam). Among them, ultraviolet rays are preferable.

In this specification, "visible light" refers to light of 380 to 780 nm. In addition, in this specification, when there is no note in particular about the measurement wavelength, the measurement wavelength is 550 nm.

In the present specification, when the liquid crystal compound is torsionally aligned in the optically anisotropic layer, the twist angle is preferably greater than 0° and less than 360°. In addition, the cholesteric liquid crystal phase described later is a phase having a periodic structure in which liquid crystal compounds are helically oriented, and has a twist angle of 360° or more.

As a characteristic point of the manufacturing method of the optically anisotropic layer of this invention, the point of carrying out a predetermined|prescribed process is mentioned.

As described in detail in the following paragraphs, in the present invention, the liquid crystal compound in the composition layer is first aligned. The oxygen concentration is low in some regions on the substrate side of the composition layer to be formed, and the oxygen concentration is high in other regions on the surface side opposite to the substrate side. Therefore, when light irradiation is performed on such a composition layer under predetermined conditions, polymerization of the liquid crystal compound is difficult to proceed in an area where the oxygen concentration is high, whereas polymerization of the liquid crystal compound is difficult to proceed in an area where the oxygen concentration is low. easy to progress In a region where the polymerization of the liquid crystal compound tends to proceed, the alignment state of the liquid crystal compound is fixed. In the case of heat treatment performed after light irradiation, the alignment state of the liquid crystal compound does not change in the region where the polymerization of the liquid crystal compound has progressed, but the orientation state of the liquid crystal compound changes in the region where the polymerization of the liquid crystal compound has hardly progressed. , the orientation state changed during the curing treatment is fixed. As a result, an optically anisotropic layer having a plurality of regions in which the alignment states of the fixed liquid crystal compounds are different along the thickness direction is produced.

The manufacturing method of the optically anisotropic layer of the present invention,

Step 1 of forming a composition layer containing a liquid crystal compound having a polymerizable group;

Step 2 of subjecting the composition layer to heat treatment to orient the liquid crystal compound in the composition layer;

After Step 2, Step 3 of irradiating the composition layer with light for 50 seconds or less and at 300 mJ/cm ² or less under conditions of an oxygen concentration of 1% by volume or more;

After step 3, step 4 of subjecting the composition layer to a heat treatment at a temperature higher than that at the time of light irradiation;

Step 4 is followed by step 5 of performing a curing treatment on the composition layer to form an optically anisotropic layer having a plurality of regions in which the alignment states of the liquid crystal compounds are different along the thickness direction.

In addition, by carrying out the said process 5, the orientation state of a liquid crystal compound is fixed.

As described later, as an aspect having regions in which the alignment states of the liquid crystal compounds are different, as described later, for example, an aspect in which the helical pitch of the cholesteric liquid crystal phase in a plurality of regions is different from each other, on the layer surface of a plurality of regions In an embodiment in which the angle of inclination of the orientation direction of the liquid crystal compound is different, and in a region formed by fixing a state in which the liquid crystal compound exhibits an isotropic phase in one of the two regions, the other region indicates an alignment state in which the liquid crystal compound is oriented. An aspect that is a region formed by fixation is exemplified.

Hereinafter, each suitable aspect of the manufacturing method of the optically anisotropic layer of the present invention will be described in detail.

<<First Embodiment>>

1st Embodiment of the manufacturing method of the optically anisotropic layer of this invention has the following steps 1A-5A. As will be described later, in the first embodiment, an optically anisotropic layer having a region formed by fixing the alignment state of the liquid crystal compound twist-aligned along the helical axis extending along the thickness direction is formed.

Step 1A: Step of forming a composition layer containing a chiral agent at least containing a photosensitive chiral agent whose helix induction force is changed by light irradiation, and a liquid crystal compound having a polymerizable group.

Step 2A: Heating the composition layer to align the liquid crystal compound in the composition layer

Step 3A: After step 2A, the composition layer is irradiated with light for 50 seconds or less and at 300 mJ/cm ² or less under conditions of an oxygen concentration of 1% by volume or more.

Step 4A: After step 3A, the composition layer is subjected to heat treatment at a temperature higher than that during light irradiation

Step 5A: After step 4A, the composition layer is cured to form an optically anisotropic layer having a plurality of regions in which the alignment states of the liquid crystal compounds are different along the thickness direction.

As will be described later, in the first embodiment, in order to manufacture an optically anisotropic layer having the above characteristics, the total content of chiral agents (total content of all chiral agents) in the composition layer is the total mass of the liquid crystal compound. , it is preferably 5.0% by mass or less.

Hereinafter, the procedure of each process is explained in detail.

<Process 1A>

Step 1A is a step of forming a composition layer containing a chiral agent containing at least a photosensitive chiral agent whose helical organic force changes upon irradiation with light, and a liquid crystal compound having a polymerizable group. By carrying out this process, the composition layer to which the light irradiation process mentioned later is performed is formed.

Below, first, the material used in this process is demonstrated in detail, and then the procedure of a process is demonstrated in detail.

(chiral agent)

The composition layer of Step 1A contains a chiral agent including at least a photosensitive chiral agent whose spiral induction force changes upon light irradiation. First, a photosensitive chiral agent whose helix induction force is changed by light irradiation will be described in detail.

In addition, the spiral induction force (HTP) of a chiral agent is a factor showing the spiral orientation ability represented by the following formula (A).

Equation (A) HTP = 1/(length of helical pitch (unit: μm) × concentration of chiral agent in liquid crystal compound (% by mass)) [μm ^-1 ]

The length of the helical pitch refers to the length of the pitch P (= helical period) of the helical structure of the cholesteric liquid crystal phase, and can be measured by the method described on page 196 of the Liquid Crystal Handbook (published by Maruzen Co., Ltd.).

The photosensitive chiral agent whose helix induction force changes with light irradiation (hereinafter, simply referred to as "chiral agent A") may be liquid crystalline or non-liquid crystalline. Chiral agent A generally contains an asymmetric carbon atom in many cases. In addition, the chiral agent A may be a condensed asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom.

The chiral agent A may be a chiral agent whose helix induction force increases or decreases upon light irradiation. Among them, a chiral agent whose spiral induction force is reduced by light irradiation is preferable.

In the present specification, "increase and decrease in helix induction force" refers to an increase and decrease when the initial (before light irradiation) helix direction of chiral agent A is referred to as "positive". Therefore, when the spiral induction force continues to decrease due to light irradiation and the spiral direction becomes “negative” by exceeding 0 (ie, inducing a spiral in a spiral direction opposite to the initial spiral direction (before light irradiation)) case), it corresponds to "a chiral agent that reduces spiral organic force".

Examples of the chiral agent A include so-called photoreactive chiral agents. A photoreactive chiral agent is a compound that has a chiral moiety and a photoreactive site whose structure is changed by light irradiation, and greatly changes the twisting force of a liquid crystal compound depending on the amount of irradiation, for example.

As an example of a photoreactive site whose structure is changed by light irradiation, a photochromic compound (Kingo Uchida, Masahiro Irie, Kagaku Kogyo, vol. 64, 640p, 1999, Kingo Uchida, Masahiro Irie, Fine Chemical, vol. 28 (9), 15p, 1999) and the like. In addition, the structural change means decomposition, addition reaction, isomerization, racemization, [2+2] photocyclization, dimerization reaction, etc., which occur due to light irradiation to the photoreactive site, and the structural change is impossible. It can be reversal. In addition, as a chiral site, for example, Hiroyuki Nohira, Chemical Review, No. Subtitles such as carbon described in 22 Chemistry of Liquid Crystals, 73p:1994 are significant.

As the chiral agent A, for example, the photoreactive chiral agent described in paragraphs 0044 to 0047 of Japanese Laid-open Patent Publication No. 2001-159709, the optically active compound described in paragraphs 0019 to 0043 of Japanese Patent Laid-Open No. 2002-179669, Japan An optically active compound described in paragraphs 0020 to 0044 of Japanese Patent Laid-Open No. 2002-179633, an optically active compound described in paragraphs 0016 to 0040 of Japanese Patent Laid-Open No. 2002-179670, and an optical active compound described in paragraphs 0017 to 0050 of Japanese Patent Laid-Open No. 2002-179668 Active compounds, optically active compounds described in paragraphs 0018 to 0044 of Japanese Laid-open Patent Publication No. 2002-180051, optically active isosorbide derivatives described in paragraphs 0016 to 0055 of Japanese Patent Laid-Open No. 2002-338575, The photoreactive optically active compound described in paragraphs 0023 to 0032, the photoreactive chiral agent described in paragraphs 0019 to 0029 of Japanese Laid-Open Patent Publication No. 2002-080851, and the optical activity described in paragraphs 0022 to 0049 of Japanese Patent Laid-Open No. 2002-179681 Compound, an optically active compound described in paragraphs 0015 to 0044 of Japanese Laid-open Patent Publication No. 2002-302487, an optically active polyester described in paragraphs 0015 to 0050 of Japanese Patent Laid-Open No. 2002-338668, paragraphs 0019 to 0019 of Japanese Patent Laid-Open No. 2003-055315 The binaphthol derivative described in 0041, the optically active fulgide compound described in paragraphs 0008 to 0043 of Japanese Laid-open Patent Publication No. 2003-073381, the optically active isosorbide derivative described in paragraphs 0015 to 0057 of Japanese Patent Laid-Open No. 2003-306490, Japanese Kokai Publication An optically active isocarbide derivative described in paragraphs 0015 to 0041 of Japanese Patent Publication No. 2003-306491, an optically active isocarbide derivative described in paragraphs 0015 to 0049 of Japanese Patent Laid-Open No. 2003-313187, and a paragraph 0015 of Japanese Patent Laid-Open No. 2003-313188 to ~0057 The optically active isomannide derivatives described, the optically active isosorbide derivatives described in paragraphs 0015 to 0049 of Japanese Laid-Open Patent Publication No. 2003-313189, the optically active polyesters/amides described in paragraphs 0015 to 0052 of Japanese Patent Laid-Open No. 2003-313292, The optically active compound described in Paragraph 0012 - 0053 of WO2018/194157, and the optically active compound described in Paragraph 0020 - 0049 of Unexamined-Japanese-Patent No. 2002-179682, etc. are mentioned.

Among them, as the chiral agent A, a compound having at least a photoisomerization site is preferred, and a photoisomerization site more preferably has a double bond capable of photoisomerization. As the photoisomerization moiety having a double bond capable of photoisomerization, a cinnamoyl moiety, a chalcone moiety, an azobenzene moiety, or a stilbene moiety is preferable in that photoisomerization is likely to occur and the helical organic force difference before and after light irradiation is large. In addition, cinnamoyl moiety, chalcone moiety or stilbene moiety is more preferable in terms of low absorption of visible light. In addition, a photoisomerization site|part corresponds to the photoreaction site|part whose structure changes by light irradiation mentioned above.

In addition, chiral agent A has a high helix induction force in the initial stage (before light irradiation) and a more excellent amount of change in helix induction force by light irradiation, and therefore has a trans-type photoisomerizable double bond. desirable.

In addition, since the chiral agent A has a low helix induction force in the initial stage (before light irradiation) and a more excellent amount of change in helix induction force by light irradiation, it has a cis-type photoisomerizable double bond. desirable.

Chiral agent A is any one selected from a binaphthyl partial structure, an isocarbide partial structure (a partial structure derived from isocarbide), and an isomannide partial structure (a partial structure derived from isomannide). It is preferable to have a partial structure of In addition, with the binaphthyl partial structure, the isosorbide partial structure, and the isomannide partial structure, the following structures are respectively intended.

A portion in which the solid line and the broken line are parallel in the binaphthyl moiety structure indicates a single bond or a double bond. In the structures shown below, * indicates a bonding position.

[Formula 1]

The chiral agent A may have a polymerizable group. The type of polymerizable group is not particularly limited, and a functional group capable of undergoing an addition polymerization reaction is preferred, and a polymerizable ethylenically unsaturated group or ring polymerizable group is more preferred, and a (meth)acryloyl group, vinyl group, styryl group, or allyl Giga is more preferable.

As the chiral agent A, a compound represented by formula (C) is preferable.

Formula (C) R-L-R

R each independently represents a group having at least one site selected from the group consisting of a cinnamoyl site, a chalcone site, an azobenzene site, and a stilbene site.

L is a divalent linking group formed by removing two hydrogen atoms from the structure represented by formula (D) (a divalent linking group formed by removing two hydrogen atoms from the binaphthyl partial structure), formula (E) The divalent linking group shown (the divalent linking group consisting of the isocarbide partial structure), or the divalent linking group represented by Formula (F) (the divalent linking group consisting of the isomannide partial structure).

In formula (E) and formula (F), * represents a bonding position.

[Formula 2]

In Step 1A, at least the chiral agent A described above is used. Step 1A may be an embodiment in which two or more chiral agents A are used, and at least one chiral agent A and at least one chiral agent whose spiral induction force does not change by light irradiation (hereinafter referred to simply as “car It is also referred to as "Iral agent B") may be used.

The chiral agent B may be liquid crystalline or non-liquid crystalline. Chiral agent B generally contains an asymmetric carbon atom in many cases. In addition, the chiral agent B may be a condensed asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom.

The chiral agent B may have a polymerizable group. As a kind of polymerizable group, the polymerizable group which chiral agent A may have is mentioned.

As the chiral agent B, a known chiral agent can be used.

The chiral agent B is preferably a chiral agent that induces a helix in the opposite direction to the chiral agent A described above. That is, for example, when the helix induced by the chiral agent A is in the right direction, the helix induced by the chiral agent B is in the left direction.

Although the molar extinction coefficients of chiral agent A and chiral agent B are not particularly limited, the molar extinction coefficient at the wavelength of light (e.g., 365 nm) irradiated in step 3A described later is 100 to 100,000 L/(mol. cm) is preferred, and 500 to 50,000 L/(mol cm) is more preferred.

The respective contents of chiral agent A and chiral agent B in the composition layer can be appropriately set depending on the characteristics (for example, retardation and wavelength dispersion) of the optically anisotropic layer to be formed. In addition, since the twist angle of the liquid crystal compound in the optically anisotropic layer largely depends on the types and concentrations of chiral agent A and chiral agent B, the alignment state of the liquid crystal compound can be controlled by adjusting them.

In the first embodiment, the total amount of chiral agents (total content of all chiral agents) in the composition layer is not particularly limited, but the total mass of the liquid crystal compound is easy to control in terms of the alignment state of the liquid crystal compound. With respect to , 5.0 mass% or less is preferable, 4.0 mass% or less is more preferable, and 2.0 mass% or less is still more preferable. The lower limit is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and still more preferably 0.05% by mass.

The content of the chiral agent A in the chiral agent is not particularly limited, but is preferably 5 to 95% by mass, relative to the total mass of the chiral agent, from the viewpoint of easy control of the alignment state of the liquid crystal compound. 90 mass % is more preferable.

(liquid crystal compound)

The composition layer of Step 1A contains a liquid crystal compound having a polymerizable group.

The type of liquid crystal compound is not particularly limited. In general, liquid crystal compounds can be classified into rod-shaped liquid crystal compounds (rod-shaped liquid crystal compounds) and disk-shaped liquid crystal compounds (discotic liquid crystal compounds) from their shapes. In addition, liquid crystal compounds can be classified into low molecular type and high molecular type. Polymers generally refer to those having a polymerization degree of 100 or higher (Polymer Physics/Phase Transition Dynamics, Masao Doi, page 2, Iwanami Shoten, 1992). Although any liquid crystal compound may be used in the present invention, it is preferable to use a rod-like liquid crystal compound or a discotic liquid crystal compound, and it is more preferable to use a rod-like liquid crystal compound. Two or more types of rod-like liquid crystal compounds, two or more types of discotic liquid crystal compounds, or a mixture of rod-like liquid crystal compounds and discotic liquid crystal compounds may be used.

Moreover, as a rod-shaped liquid crystal compound, what is described in Claim 1 of Unexamined-Japanese-Patent No. 11-513019, and Paragraph 0026 - 0098 of Unexamined-Japanese-Patent No. 2005-289980 can be used suitably, for example.

As a discotic liquid crystal compound, Paragraph 0020 of Unexamined-Japanese-Patent No. 2007-108732 - 0067 and Paragraph 0013 - 0108 of Unexamined-Japanese-Patent No. 2010-244038 can be used suitably, for example.

The type of polymerizable group of the liquid crystal compound is not particularly limited, and a functional group capable of addition polymerization is preferable, and a polymerizable ethylenically unsaturated group or ring polymerizable group is more preferable, and (meth)acryloyl group, vinyl group, and styryl group. , or an allyl group is more preferred.

In addition, the optically anisotropic layer produced in the present invention is a layer formed by fixing a liquid crystal compound having a polymerizable group (a rod-like liquid crystal compound or discotic liquid crystal compound having a polymerizable group) by polymerization or the like, and is no longer liquid crystalline after becoming a layer. need not indicate

The content of the liquid crystal compound in the composition layer is not particularly limited, but is preferably 60% by mass or more, and more preferably 70% by mass or more with respect to the total mass of the composition layer, from the viewpoint of easy control of the alignment state of the liquid crystal compound. do. The upper limit is not particularly limited, but is preferably 99% by mass or less, and more preferably 97% by mass or less.

(other ingredients)

The composition layer may contain components other than the chiral agent and the liquid crystal compound.

For example, the composition layer may contain a polymerization initiator. When the composition layer contains a polymerization initiator, polymerization of the liquid crystal compound having a polymerizable group proceeds more efficiently.

Examples of the polymerization initiator include known polymerization initiators, including photopolymerization initiators and thermal polymerization initiators, with photopolymerization initiators being preferred. In particular, a polymerization initiator that is sensitive to light irradiated in step 5A described later is preferable.

The polymerization initiator preferably has a maximum molar extinction coefficient among the wavelengths of light irradiated in step 3A and is 0.1 times or less of the maximum molar extinction coefficient among wavelengths of light irradiated in step 5A.

In addition, the molar extinction coefficient of the polymerization initiator at the wavelength of light irradiation in step 3A is preferably 5000 L/(mol cm) or less, and 4000 L/(mol cm) or less is more preferable, and 3000 L/(mol cm) or less is more preferable. The lower limit is not particularly limited, and is preferably 0 L/(mol·cm), but is often 30 L/(mol·cm) or more.

The content of the polymerization initiator in the composition layer is not particularly limited, but is preferably 0.01 to 20% by mass, more preferably 0.5 to 10% by mass, based on the total mass of the composition layer.

The composition layer may contain a photosensitizer.

The kind of photosensitizer is not particularly limited, and known photosensitizers are exemplified.

In addition, the molar extinction coefficient at the wavelength of light irradiation in step 3A of the photosensitizer is preferably 5000 L/(mol cm) or less, and 4800 L/( mol cm) or less is more preferable, and 4500 L/(mol cm) or less is still more preferable. The lower limit is not particularly limited, and is preferably 0 L/(mol·cm), but is often 30 L/(mol·cm) or more.

The content of the photosensitizer in the composition layer is not particularly limited, but is preferably 0.01 to 20% by mass, and more preferably 0.5 to 10% by mass, based on the total mass of the composition layer.

The composition layer may contain a polymerizable monomer different from the liquid crystal compound having a polymerizable group. Examples of the polymerizable monomer include radically polymerizable compounds and cationically polymerizable compounds, and polyfunctional radically polymerizable monomers are preferred. As a polymerizable monomer, Paragraph 0018 in Unexamined-Japanese-Patent No. 2002-296423 - the polymerizable monomer of 0020 are mentioned, for example.

The content of the polymerizable monomer in the composition layer is not particularly limited, but is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, based on the total mass of the liquid crystal compound.

The composition layer may contain a surfactant. Examples of the surfactant include conventionally known compounds, but fluorine-based compounds are preferable. Specifically, the compound described in Paragraph 0028 in Unexamined-Japanese-Patent No. 2001-330725 - 0056, and the compound described in Paragraph 0069 - 0126 in Unexamined-Japanese-Patent No. 2003-295212 are mentioned, for example.

The composition layer may contain a polymer. Cellulose ester is mentioned as a polymer. As a cellulose ester, what was described in Paragraph 0178 in Unexamined-Japanese-Patent No. 2000-155216 is mentioned.

The content of the polymer in the composition layer is not particularly limited, but is preferably 0.1 to 10% by mass, more preferably 0.1 to 8% by mass, based on the total mass of the liquid crystal compound.

In addition to the above, the composition layer may contain an additive (alignment control agent) that promotes horizontal alignment or vertical alignment in order to bring the liquid crystal compound into a horizontal alignment state or a vertical alignment state.

(Board)

As will be described later, when forming the composition layer, it is preferable to form the composition layer on the substrate.

The substrate is a plate supporting the composition layer.

As the substrate, a transparent substrate is preferable. In addition, with a transparent substrate, a substrate with visible light transmittance of 60% or more is intended, and the transmittance thereof is preferably 80% or more, more preferably 90% or more.

The retardation value (Rth (550)) in the thickness direction of the substrate at a wavelength of 550 nm is not particularly limited, but is preferably -110 to 110 nm, and more preferably -80 to 80 nm.

The in-plane retardation value (Re(550)) of the substrate at a wavelength of 550 nm is not particularly limited, but is preferably 0 to 50 nm, more preferably 0 to 30 nm, and still more preferably 0 to 10 nm.

As the material for forming the substrate, a polymer having excellent optical performance, transparency, mechanical strength, thermal stability, moisture shielding property, and isotropy is preferable.

As a polymer film that can be used as a substrate, for example, a cellulose acylate film (for example, a cellulose triacetate film (refractive index 1.48), a cellulose diacetate film, a cellulose acetate butylate film, a cellulose acetate propionate film), Polyolefin films such as polyethylene and polypropylene, polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone films, polyacrylic films such as polymethyl methacrylate, polyurethane films, polycarbonate films, A sulfone film, a polyether film, a polymethylpentene film, a polyether ketone film, a (meth)acrylonitrile film, and a polymer film having an alicyclic structure (norbornene resin (Atone: trade name, manufactured by JSR Corporation, amorphous) polyolefin (Zeonex: trade name, manufactured by Nippon Zeon Co., Ltd.)).

Among them, as the material of the polymer film, triacetyl cellulose, polyethylene terephthalate, or a polymer having an alicyclic structure is preferable, and triacetyl cellulose is more preferable.

The substrate may contain various additives (eg, optical anisotropy regulator, wavelength dispersion regulator, fine particles, plasticizer, ultraviolet inhibitor, deterioration inhibitor, release agent, etc.).

The thickness of the substrate is not particularly limited, but is preferably 10 to 200 μm, more preferably 10 to 100 μm, and still more preferably 20 to 90 μm. In addition, the substrate may consist of a plurality of laminated sheets. The substrate may be subjected to surface treatment (eg, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment) on the surface of the substrate in order to improve adhesion with the layer provided thereon.

Moreover, you may provide an adhesive layer (undercoat layer) on a board|substrate.

In addition, in order to impart sliding properties in the conveyance step to the substrate or to prevent adhesion of the back surface and the surface after winding, inorganic particles having an average particle diameter of about 10 to 100 nm are mixed at a solid content mass ratio of 5 to 40% by mass A polymer layer may be disposed on one side of the substrate.

The substrate may be a so-called temporary support body. That is, after carrying out the production method of the present invention, the substrate may be separated from the optically anisotropic layer.

Moreover, you may perform a rubbing process directly on the surface of a board|substrate. That is, you may use the board|substrate on which the rubbing process was performed. The direction of the rubbing treatment is not particularly limited, and an optimal direction is appropriately selected according to the direction in which the liquid crystal compound is to be oriented.

For the rubbing treatment, a treatment method widely employed as a liquid crystal alignment treatment step of a liquid crystal display (LCD) can be applied. That is, a method of obtaining orientation can be used by rubbing the surface of the substrate in a certain direction using paper, gauze, felt, rubber, nylon fiber, polyester fiber, or the like.

An alignment film may be disposed on the substrate.

The alignment film is a rubbing treatment of an organic compound (preferably a polymer), oblique deposition of an inorganic compound, formation of a layer having microgrooves, or an organic compound (eg, LB film) by the Langmuir-Blodgett method. , ω-tricosanoic acid, dioctadecylmethylammonium chloride, methyl stearylate).

Also known is an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation (preferably polarized light).

The alignment film is preferably formed by a polymer rubbing treatment.

As the polymer contained in the alignment film, for example, a methacrylate-based copolymer, a styrene-based copolymer, polyolefin, polyvinyl alcohol, modified polyvinyl alcohol, poly( N-methylolacrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethylcellulose, and polycarbonate. Moreover, a silane coupling agent can also be used as a polymer.

Among them, water-soluble polymers (e.g., poly(N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and denatured polyvinyl alcohol) are preferred, and gelatin, polyvinyl alcohol, and denatured polyvinyl alcohol are more preferred. , polyvinyl alcohol or modified polyvinyl alcohol is more preferable.

As described above, the alignment layer may be formed by coating a solution containing the above polymer as an alignment layer forming material and optional additives (eg, a crosslinking agent) on a substrate, followed by heat drying (crosslinking) and rubbing. can

(Procedure of step 1A)

In Step 1A, a composition layer containing the components described above is formed, but the procedure is not particularly limited. For example, a method of applying a composition containing the above-described chiral agent and a liquid crystal compound having a polymerizable group onto a substrate and, if necessary, drying it (hereinafter, simply referred to as "coating method"), and , a method of forming a separate composition layer and transferring it onto a substrate. Among them, the application method is preferable from the viewpoint of productivity.

Hereinafter, the application method is explained in detail.

In the composition used in the application method, the above-mentioned chiral agent, liquid crystal compound having a polymerizable group, and other components used as necessary (eg, polymerization initiator, polymerizable monomer, surfactant, and polymer) etc.) are included.

The content of each component in the composition is preferably adjusted so as to be the content of each component in the composition layer described above.

The application method is not particularly limited, and examples thereof include a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method.

Further, if necessary, a treatment of drying the coating film applied on the substrate may be performed after application of the composition. By performing the drying treatment, the solvent can be removed from the coating film.

The film thickness of the coating film is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, and still more preferably 0.5 to 10 μm.

<Process 2A>

Step 2A is a step of subjecting the composition layer to heat treatment to orient the liquid crystal compound in the composition layer. By performing this step, the liquid crystal compound in the composition layer is brought into a predetermined alignment state.

As conditions for heat treatment, optimum conditions are selected depending on the liquid crystal compound used.

Among them, the heating temperature is often 25 to 250°C, more often 40 to 150°C, and more often 50 to 130°C.

As heating time, it is 0.1 to 60 minutes in many cases, and 0.2 to 5 minutes in many cases.

The alignment state of the liquid crystal compound obtained in step 2A changes according to the spiral induction force of the chiral agent described above.

For example, as will be described later, a first region formed by fixing the orientation state of the liquid crystal compound twisted along a helical axis extending along the thickness direction, and a second region obtained by fixing the orientation state of the liquid crystal compound homogeneously aligned In order to form an optically anisotropic layer having , in the thickness direction, the absolute value of the weighted average helical induction force of the chiral agent in the composition layer formed by step 1A is preferably 0.0 to 1.9 μm ^-1 , and is 0.0 to 1.9 μm -1 . It is more preferably 1.5 μm ^-1 , more preferably 0.0 to 1.0 μm ^-1 , particularly preferably 0.0 to 0.5 μm ^-1 , more particularly preferably 0.0 to 0.02 μm ^-1 , and zero is the most desirable.

When the absolute value of the weighted average helical organic force of the chiral agent in the composition layer is within the above range, when step 2A is performed, the liquid crystal compound in the composition is homogeneously oriented, or the liquid crystal compound in the composition layer is a spiral extending along the thickness direction. It is torsionally oriented along the axis.

In addition, the weighted average spiral organic force of a chiral agent is, when two or more kinds of chiral agents are contained in the composition, the spiral organic force of each chiral agent contained in the composition layer and each chiral agent in the composition layer. It represents the sum of the values obtained by dividing the product of the concentrations (% by mass) by the total concentration (% by mass) of the chiral agent in the composition layer. For example, when two types of chiral agents (chiral agent X and chiral agent Y) are used together, it is represented by the following formula (B).

Formula (B) weighted average helix induction force (μm ^-1 ) = (helix induction force of chiral agent X (μm ^-1 ) × concentration of chiral agent X in the composition layer (% by mass) + chiral agent Y of the spiral induction force (μm ^-1 ) × concentration of chiral agent Y in the composition layer (mass %) / (concentration of chiral agent X in the composition layer (mass %) + Ka in the composition layer Concentration of Yralze Y (% by mass))

However, in the above formula (B), when the spiral direction of the chiral agent is rightward winding, the spiral induction force is taken as a positive value. In the case where the spiral direction of the chiral agent is leftward winding, the spiral induction force is taken as a negative value. That is, for example, in the case of a chiral agent having a helix induction force of 10 μm ^-1 , and when the helix direction of the helix induced by the chiral agent is rightward winding, the helix induction force is expressed as 10 μm ^-1 . On the other hand, when the helix direction of the helix induced by the chiral agent is leftward winding, the helix induction force is expressed as -10 μm ^-1 .

When the absolute value of the weighted average spiral organic force of the chiral agent in the composition layer formed by step 1A is 0, as shown in FIG. 1, the liquid crystal compound (LC) is homogeneously aligned on the substrate 10 A composition layer 12 is formed. 1 is a schematic diagram of a cross section of the substrate 10 and the composition layer 12 . In addition, in the composition layer 12 shown in FIG. 1, chiral agent A and chiral agent B exist at the same concentration, and the spiral direction induced by chiral agent A is left-handed, and by chiral agent B It is assumed that the spiral direction to be induced is right winding. In addition, the absolute value of the spiral induction force of the chiral agent A and the absolute value of the spiral induction force of the chiral agent B are assumed to be the same.

In the present specification, homogeneous alignment means a state in which the molecular axes of the liquid crystal compound (for example, the long axis in the case of a rod-like liquid crystal compound) are aligned horizontally and in the same direction with respect to the surface of the composition layer (optical uniaxial).

Here, horizontal is not strictly required to be horizontal, but means an orientation in which the average molecular axis of the liquid crystal compound in the composition layer and the surface of the composition layer have an inclination angle of less than 20 degrees.

In addition, the same orientation does not strictly require that they be the same orientation, but when the slow axis orientations are measured at 20 arbitrary positions in the plane, the maximum difference (20 It is assumed that the difference between the two slow axis orientations of which the difference is the largest among the slow axis orientations of the dog) is less than 10°.

In addition, in FIG. 1, the embodiment in which the liquid crystal compound (LC) is homogeneously aligned has been described, but as long as the liquid crystal compound is in a predetermined alignment state, it is not limited to this embodiment, and for example, described in detail in the following paragraphs. As such, the aspect in which the liquid crystal compound is torsionally aligned along the helical axis extending along the thickness direction of the composition layer may be used.

<Process 3A>

Step 3A is a step in which, after step 2A, the composition layer is irradiated with light for 50 seconds or less and at 300 mJ/cm ^{2 or} less under conditions of an oxygen concentration of 1% by volume or more. Below, the mechanism of this process is demonstrated using drawing. In the following, an example in which step 3A is performed on the composition layer 12 shown in FIG. 1 will be described as a representative example.

As shown in FIG. 2, in step 3A, light is irradiated from the direction opposite to the composition layer 12 side of the substrate 10 (direction of the white arrow in FIG. 2) under the condition of an oxygen concentration of 1% by volume or more. . 2, light irradiation is performed from the substrate 10 side, but may be performed from the composition layer 12 side.

At that time, comparing the lower region 12A on the substrate 10 side of the composition layer 12 with the upper region 12B on the opposite side to the substrate 10 side, the surface of the upper region 12B is air. side, the oxygen concentration in the upper region 12B is high, and the oxygen concentration in the lower region 12A is low. Therefore, when the composition layer 12 is irradiated with light, polymerization of the liquid crystal compound tends to proceed in the lower region 12A, and the alignment state of the liquid crystal compound is fixed. In addition, chiral agent A is also present in the lower region 12A, and chiral agent A is also photosensitized, and the spiral induction force is changed. However, since the alignment state of the liquid crystal compound is fixed in the lower region 12A, even if step 4A of heating the light-irradiated composition layer to be described later is performed, the alignment state of the liquid crystal compound does not change. don't

In addition, since the oxygen concentration is high in the upper region 12B, even if light is irradiated, polymerization of the liquid crystal compound is inhibited by oxygen and the polymerization does not proceed easily. And, since the chiral agent A is also present in the upper region 12B, the chiral agent A is photosensitized and the spiral induction force is changed. Therefore, when step 4A described later is performed, the alignment state of the liquid crystal compound changes according to the changed spiral induction force.

That is, by performing step 3A, fixation of the alignment state of the liquid crystal compound tends to proceed in the region (lower region) of the composition layer on the substrate side. In addition, in the region (upper region) on the opposite side of the substrate side of the composition layer, it is difficult to fix the alignment state of the liquid crystal compound, and the spiral induction force is changed depending on the photosensitized chiral agent A. .

Step 3A is performed under conditions of an oxygen concentration of 1% by volume or more. Among them, the oxygen concentration is preferably 2% by volume or more, and more preferably 5% by volume or more, because regions in which the orientation states of the liquid crystal compounds are different are easily formed in the optically anisotropic layer. Although the upper limit is not particularly limited, 100% by volume is exemplified.

The light irradiation time in step 3A is 50 seconds or less, preferably 30 seconds or less, and more preferably 10 seconds or less from the viewpoint of easy formation of a predetermined optically anisotropic layer and productivity. The lower limit is not particularly limited, but is preferably 0.1 second or longer, and more preferably 0.2 second or longer, from the viewpoint of curing the liquid crystal compound.

The irradiation amount of the light irradiation in step 3A is 300 mJ/cm ² or less, preferably 250 mJ/cm ^{2 or} less, and more preferably 200 mJ/cm ^{2 or} less from the viewpoint of easy formation of a predetermined optically anisotropic layer and productivity. desirable. The lower limit is not particularly limited, but is preferably 1 mJ/cm ² or more, and more preferably 5 mJ/cm ² or more, from the viewpoint of curing the liquid crystal compound.

If the time and amount of light irradiation do not satisfy the above requirements, the predetermined optically anisotropic layer cannot be formed.

In addition, it is preferable that light irradiation in step 3A in the first embodiment is performed at 15 to 70°C (preferably 25 to 50°C).

The light used for light irradiation may be any light to which the chiral agent A is sensitive. That is, the light used for light irradiation is not particularly limited as long as it is active light or radiation that changes the helical organic force of chiral agent A, and examples include bright line spectrum of mercury lamps, deep ultraviolet rays represented by excimer lasers, and extreme ultraviolet rays. , X-rays, ultraviolet rays, and electron beams. Among them, ultraviolet rays are preferable.

<Process 4A>

Step 4A is a step of subjecting the composition layer to a heat treatment after step 3A at a temperature higher than that at the time of light irradiation. By carrying out this step, the alignment state of the liquid crystal compound changes in the region where the spiral induction force of the chiral agent A in the composition layer to which light irradiation has been applied has changed. More specifically, this step is a step of aligning the liquid crystal compound in the composition layer that is not fixed in step 3A by subjecting the composition layer after step 3A to heat treatment at a temperature higher than that during irradiation.

Below, the mechanism of this process is demonstrated using drawing.

As described above, when step 3A is performed on the composition layer 12 shown in FIG. 1, the alignment state of the liquid crystal compound is fixed in the lower region 12A, while the liquid crystal compound is polymerized in the upper region 12B. is difficult to progress, and the alignment state of the liquid crystal compound is not fixed. Also, in the upper region 12B, the spiral induction force of the chiral agent A is changing. When such a change in the spiral induction force of the chiral agent A occurs, the force to twist the liquid crystal compound in the upper region 12B is changed compared to the state before light irradiation. This point will be explained in more detail.

As described above, chiral agent A and chiral agent B exist at the same concentration in the composition layer 12 shown in FIG. The helix direction induced by B is right winding. In addition, the absolute value of the spiral pulling force of the chiral agent A and the absolute value of the spiral pulling force of the chiral agent B are the same. Therefore, the weighted average spiral induction force of the chiral agent in the composition layer before light irradiation is zero.

The above aspect is shown in FIG. 4 . In Fig. 4, the vertical axis represents "the spiral induction force of the chiral agent (μm ^-1 ) x the concentration (mass %) of the chiral agent", and the farther the value is from zero, the greater the spiral induction force. First, the relationship between chiral agent A and chiral agent B in the composition layer before irradiation with light corresponds to the time when the amount of light irradiation is 0, and “helix induction force of chiral agent A (μm ^-1 ) × ka The absolute value of "concentration of chiral agent A (mass %)" and the absolute value of "helical induction force of chiral agent B (μm ^-1 ) × concentration of chiral agent B (mass %)" correspond to the same state. That is, the spiral induction forces of both the chiral agent A, which induces left winding, and the chiral agent B, which induces right winding, are offset.

When light irradiation is performed in the upper region 12B in such a state, and as shown in FIG. 4, the spiral induction force of the chiral agent A decreases with the amount of light irradiation, as shown in FIG. 5, the upper region ( In 12B), the weighted average helix induction force of the chiral agent increases, and the helix induction force of the right-side winding becomes stronger. That is, as for the helix induction force of the liquid crystal compound, the larger the irradiation amount, the greater the helix induction force in the direction (+) of the helix induction of the chiral agent B.

Therefore, when heat treatment is performed on the composition layer 12 after step 3A in which such a change in the weighted average spiral organic force occurs to promote reorientation of the liquid crystal compound, as shown in FIG. 3, the upper region In (12B), the liquid crystal compound (LC) is torsionally aligned along a helical axis extending along the thickness direction of the composition layer 12.

On the other hand, as described above, in the lower region 12A of the composition layer 12, since the polymerization of the liquid crystal compound proceeds during step 3A and the alignment state of the liquid crystal compound is fixed, the liquid crystal compound is not rearranged. don't

As described above, by performing step 4A, a plurality of regions having different alignment states of the liquid crystal compound are formed along the thickness direction of the composition layer.

In addition, in the above FIGS. 4 and 5, an embodiment using a chiral agent A, in which the spiral induction force is reduced by light irradiation, has been described, but this embodiment is not limited. For example, as the chiral agent A, a chiral agent whose helix induction force increases upon irradiation with light may be used. In that case, the helical induction force of the chiral agent A increases due to light irradiation, and the liquid crystal compound is torsionally oriented in the direction of rotation in which the chiral agent A is induced.

In addition, in the above FIGS. 4 and 5, an embodiment in which chiral agent A and chiral agent B are used together has been described, but this embodiment is not limited. For example, an aspect using two types of chiral agent A may be used. Specifically, an aspect in which chiral agent A1, which induces left-side winding, and chiral agent A2, which induces right-side winding, are used together. Chiral agents A1 and A2 may each independently be a chiral agent increasing the helix induction force or a chiral agent in which the helix induction force decreases. For example, a chiral agent that induces left-side winding and whose spiral-induced force increases by light irradiation, and a chiral agent that induces right-side winding and whose spiral-induced force decreases by light irradiation It is also possible to use rales in combination.

Heat treatment is performed at a temperature higher than that at the time of light irradiation.

The difference between the temperature of the heat treatment and the temperature during light irradiation is preferably 5°C or higher, more preferably 10 to 110°C, more preferably 20 to 110°C.

The temperature of the heat treatment is higher than the temperature at the time of light irradiation, and is preferably a temperature at which the non-fixed liquid crystal compound in the composition layer is oriented, and more specifically, it is often 35 to 250 ° C., and 50 to 150 ° C. There are more cases of , more cases of more than 50 ℃ and less than 150 ℃, and especially many cases of 60 ~ 130 ℃.

As heating time, it is 0.01 to 60 minutes in many cases, and 0.03 to 5 minutes in many cases.

In addition, the absolute value of the weighted average spiral organic force of the chiral agent in the composition layer after light irradiation is not particularly limited, but the weighted average spiral organic force of the chiral agent in the composition layer after light irradiation and the weighted average spiral organic force before light irradiation The absolute value of the difference is preferably 0.05 µm ^-1 or more, more preferably 0.05 to 10.0 µm ^-1 , and still more preferably 0.1 to 10.0 µm ^-1 .

<Process 5A>

Step 5A is a step of forming an optically anisotropic layer having a plurality of regions having different orientation states of liquid crystal compounds along the thickness direction by subjecting the composition layer to a curing treatment after step 4A. By carrying out this process, the alignment state of the liquid crystal compound in the composition layer is fixed, and as a result, a predetermined optically anisotropic layer is formed. Further, for example, when the curing treatment is performed on the composition layer 12 shown in FIG. 3 described above, the first region obtained by fixing the alignment state of the liquid crystal compound twisted along the helical axis extending along the thickness direction An optically anisotropic layer having, along the thickness direction, a second region formed by fixing the alignment state of the liquid crystal compound subjected to homogeneous alignment is formed.

The method of curing treatment is not particularly limited, and photocuring treatment and thermal curing treatment are exemplified. Among them, light irradiation treatment is preferred, and ultraviolet irradiation treatment is more preferred.

For ultraviolet irradiation, a light source such as an ultraviolet lamp is used.

The irradiation amount of light (eg, ultraviolet rays) is not particularly limited, but is generally preferably about 100 to 800 mJ/cm ² .

The atmosphere at the time of light irradiation is not particularly limited, and light irradiation may be performed under air or light irradiation may be performed under an inert atmosphere. In particular, light irradiation is preferably performed at an oxygen concentration of less than 1% by volume.

When photocuring is performed as the curing treatment, the temperature conditions at the time of photocuring are not particularly limited, as long as the temperature at which the alignment state of the liquid crystal compound in step 4A is maintained, and the temperature of heat treatment in step 4A and photocuring The difference in temperature is preferably within 100°C and more preferably within 80°C.

In addition, it is preferable that the temperature at the time of the heat treatment of step 4A and the temperature at the time of photocuring treatment are the same, or the temperature at the time of photocuring treatment is a lower temperature.

In the optically anisotropic layer obtained by performing the curing treatment, the alignment state of the liquid crystal compound is fixed.

In addition, in this specification, the "fixed" state is the most typical and preferred embodiment in which the alignment of the liquid crystal compound is maintained. It is not limited to that only, and specifically, in the temperature range of usually 0 to 50 ° C., and -30 to 70 ° C. under more severe conditions, the layer has no fluidity, and the orientation form does not change due to exterior or external force. It is more preferable that it does not generate|occur|produce, and it is a state which can continue to stably maintain a fixed orientation form.

Further, in the optically anisotropic layer, the final composition in the layer need not exhibit liquid crystallinity anymore.

The thickness of the optically anisotropic layer is not particularly limited, but is preferably 0.05 to 10 μm, more preferably 0.1 to 8.0 μm, and still more preferably 0.2 to 6.0 μm.

In the embodiment shown in FIG. 3 described above, the first region formed by fixing the alignment state of the liquid crystal compound twisted and aligned rightward along the helical axis extending along the thickness direction, and the orientation state of the liquid crystal compound homogeneously aligned is fixed, An optically anisotropic layer having a second region formed along the thickness direction is fabricated, but the present invention is not limited to the above aspect.

For example, the twist orientation of the liquid crystal compound may be left twisted. That is, the direction of twist alignment of the liquid crystal compound may be either left twist (counterclockwise twist) or right twist (clockwise twist).

Further, as the orientation state of the liquid crystal compound in the second region, an orientation other than homogeneous orientation may be used. When the liquid crystal compound is a rod-like liquid crystal compound, the orientation state is, for example, nematic orientation (nematic phase state), smectic orientation (state in which smectic phase is formed), cholesteric orientation (state in which cholesteric phase is formed), and hybrid orientation. When the liquid crystal compound is a discotic liquid crystal compound, examples of the alignment state include nematic alignment, columnar alignment (a state in which a columnar phase is formed), and cholesteric alignment.

Moreover, a well-known method is mentioned as a method of specifying the orientation state of a liquid crystal compound. For example, a method of specifying the alignment state of the liquid crystal compound by observing the cross section of the optically anisotropic layer with a polarization microscope is exemplified.

In the embodiment shown in Fig. 3, the optically anisotropic layer has a region in which the two liquid crystal compounds are in different alignment states. You may have three or more areas.

When the optically anisotropic layer has a region in which the two liquid crystal compounds are in different alignment states, the ratio of the thickness of the thicker region of the two regions to the thickness of the thinner region of the two regions is not particularly limited, but 1 More than 9 or less is preferable, and more than 1 and 4 or less are more preferable.

In addition, when the thicknesses of the two regions are the same, the ratio is 1.

In addition, the optically anisotropic layer in the first embodiment includes a first region formed by fixing the alignment state of the liquid crystal compound twist-aligned along a helical axis extending along the thickness direction, and a first region along the helical axis extending along the thickness direction. It may be an optical anisotropic layer having a second region along the thickness direction formed by fixing the alignment state of the twisted liquid crystal compound at a twist angle different from .

As a method for forming a region having different twist angles of liquid crystal compounds as described above, for example, the absolute value of the weighted average spiral induction force of the chiral agent in the composition layer formed by the above-described step 1A is increased (e.g., For example, a method of exceeding 0 μm ^-1 ) may be mentioned. When the absolute value of the weighted average spiral induction force of the chiral agent in the composition layer formed by step 1A is large, first, as shown in FIG. 6, in the composition layer 120 subjected to step 2, along the thickness direction The liquid crystal compound is torsionally aligned along the extending helical axis. When the above-described process is performed on such a composition layer, the torsion orientation of the liquid crystal compound is fixed as it is in the region (lower region 120A in FIG. In the region in the composition layer (upper region 120B in FIG. 7 ), the spiral inducing force changes, and as a result, regions having different twist angles of the liquid crystal compound can be formed after Step 5A is performed.

The optical properties in the optically anisotropic layer in the first embodiment are not particularly limited, and an optimum value is selected depending on the application. Hereinafter, as an example, the first region formed by fixing the alignment state of the liquid crystal compound twist-aligned along the helical axis extending along the thickness direction and the orientation state of the liquid crystal compound homogeneously aligned is fixed, The case of the optically anisotropic layer having the second region formed along the thickness direction will be described in detail.

When the thickness of the first region of the optically anisotropic layer is d1 and the refractive index anisotropy of the first region measured at a wavelength of 550 nm is Δn1, the optically anisotropic layer can be suitably applied to the circular polarizing plate, the first region It is preferable to satisfy the following formula (1A-1).

Equation (1A-1) 100nm≤Δn1d1≤240nm

Among them, it is more preferable to satisfy the formula (1A-2), and even more preferable to satisfy the formula (1A-3).

Equation (1A-2) 120nm≤Δn1d1≤220nm

Equation (1A-3) 140nm≤Δn1d1≤200nm

The absolute value of the twist angle of the liquid crystal compound in the first region is not particularly limited, but is preferably 50 to 110°, and more preferably 60 to 100°, from the viewpoint that the optically anisotropic layer can be suitably applied to a circular polarizing plate. do.

In addition, first, torsionally align the liquid crystal compound, with the thickness direction of the first region as an axis, from one surface of the first region (surface on the substrate 10 side in FIG. 3) to the other surface (in FIG. 3). It is intended that the liquid crystal compound up to the surface on the opposite side to the substrate 10 side is twisted. Therefore, the twist angle is defined by the molecular axis of the liquid crystal compound on one surface of the first region (long axis in the case of a rod-shaped liquid crystal compound) and the molecular axis of the liquid crystal compound on the other surface of the first region. means angle.

The method of measuring the twist angle is measured using Axometrics' Axoscan and using the company's device analysis software.

In addition, when the thickness of the second region of the optically anisotropic layer is d2 and the refractive index anisotropy of the second region measured at a wavelength of 550 nm is Δn2, the optically anisotropic layer can be suitably applied to the circular polarizing plate. The region preferably satisfies the following formula (2A-1).

Equation (2A-1) 100nm≤Δn2d2≤240nm

Among them, it is more preferable to satisfy the expression (2A-2), and even more preferable to satisfy the expression (2A-3).

Equation (2A-2) 120nm≤Δn2d2≤220nm

Equation (2A-3) 140nm≤Δn2d2≤200nm

The second region is a region obtained by fixing the alignment state of the homogeneously aligned liquid crystal compound. The definition of homogeneous orientation is as described above.

Further, the difference between Δn1d1 and Δn2d2 is not particularly limited, but is preferably -50 to 50 nm, and more preferably -30 to 30 nm from the viewpoint that the optically anisotropic layer can be suitably applied to a circular polarizing plate.

Further, in the optically anisotropic layer in the first embodiment, two regions formed by fixing the alignment state of liquid crystal compounds twisted and aligned along a helical axis extending along the thickness direction are included, and one region is region A and the other region When is region B, the thickness of region A is dA, and the refractive index anisotropy layer in region A measured at a wavelength of 550 nm is ΔA, region A is from the point that the optically anisotropic layer can be suitably applied to the circular polarizing plate. , it is preferable to satisfy the following formula (3A-1).

Equation (3A-1) 205nm≤ΔnAdA≤345nm

Among them, it is more preferable to satisfy the formula (3A-2), and even more preferable to satisfy the formula (3A-3).

Equation (3A-2) 225nm≤ΔnAdA≤325nm

Equation (3A-3) 245nm≤ΔnAdA≤305nm

The absolute value of the twist angle of the liquid crystal compound in the region A is not particularly limited, but is preferably greater than 0° and less than or equal to 60°, and more preferably 10 to 50°, from the viewpoint of suitably applying the optically anisotropic layer to a circular polarizing plate. desirable.

When the refractive index anisotropy of region B measured at the thickness of region B at d2 and a wavelength of 550 nm is ΔnB, the optically anisotropic layer can be suitably applied to the circular polarizing plate. It is desirable to satisfy

Equation (4A-1) 70nm≤ΔnBdB≤210nm

Among them, it is more preferable to satisfy the formula (4A-2), and even more preferable to satisfy the formula (4A-3).

Equation (4A-2) 90nm≤ΔnBdB≤190nm

Equation (4A-3) 110nm≤ΔnBdB≤170nm

The absolute value of the twist angle of the liquid crystal compound in the region B is not particularly limited, but is preferably 50 to 110°, more preferably 60 to 100°, from the viewpoint that the optically anisotropic layer can be suitably applied to a circular polarizing plate. .

In addition, as in the above aspect, when the optically anisotropic layer formed by the first embodiment of the method for producing an optically anisotropic layer of the present invention has two regions in which the orientation state of the liquid crystal compound is different along the thickness direction (hereinafter, two The regions are referred to as region X and region Y.), the slow axis of the surface of the region X on the region Y side and the slow axis of the surface of the region Y on the region X side are often parallel.

The optical properties in the optically anisotropic layer in the first embodiment are not limited to the above-described aspects, and for example, when the optically anisotropic layer has two regions in which the alignment states of the liquid crystal compounds are different along the thickness direction, It is preferable that the two regions satisfy the optical characteristics (torsion angle of the liquid crystal compound, Δnd, ReB, and slow axis relationship) of the first optically anisotropic layer and the second optically anisotropic layer, respectively, described in Japanese Patent Publication No. 5960743.

As another aspect, when the optically anisotropic layer has two regions in the thickness direction, the two regions are the optical properties of the first optically anisotropic layer and the second optically anisotropic layer described in Japanese Patent Publication No. 5753922 (liquid crystal compound It is preferable to satisfy the twist angle, Δn1d1, Δn2d2, relationship of the slow axis).

The optically anisotropic layer in the first embodiment preferably exhibits reverse wavelength dispersion.

That is, the in-plane retardation Re (450) measured at a wavelength of 450 nm of the optical anisotropic layer, the in-plane retardation Re (550) measured at a wavelength of 550 nm of the optical anisotropic layer, and the in-plane retardation measured at a wavelength of 650 nm of the optical anisotropic layer Re (650), which is retardation, preferably has a relationship of Re (450) ≤ Re (550) ≤ Re (650).

The optical properties of the optically anisotropic layer in the first embodiment are not particularly limited, but it is preferable to function as a λ/4 plate.

The λ/4 plate is a plate having a function of converting linearly polarized light of a predetermined specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light), and the in-plane retardation Re(λ) at a specific wavelength λnm is Re It refers to a plate (optically anisotropic layer) that satisfies (λ)=λ/4.

This formula only needs to be achieved at any wavelength in the visible light range (eg 550 nm), but the in-plane retardation Re(550) at a wavelength of 550 nm satisfies the relationship of 110 nm ≤ Re (550) ≤ 180 nm It is desirable to do

<<Second Embodiment>>

2nd Embodiment of the manufacturing method of the optically anisotropic layer of this invention has the following steps 1B-5B. As will be described later, in the second embodiment, an optically anisotropic layer having a region formed by fixing a cholesteric liquid crystal phase is formed.

Step 1B: Step of forming a composition layer containing a chiral agent containing at least a photosensitive chiral agent whose helix organic force changes upon irradiation with light, and a liquid crystal compound having a polymerizable group.

Step 2B: Heating the composition layer to align the liquid crystal compound in the composition layer to form a cholesteric liquid crystal phase

Step 3B: After Step 2B, the composition layer is irradiated with light for 50 seconds or less under conditions of an oxygen concentration of 1% by volume or more, and at 300 mJ/cm ^{2 or} less.

Step 4B: After step 3B, the composition layer is subjected to heat treatment at a temperature higher than that during light irradiation

Step 5B: After step 4B, the composition layer is cured to form an optically anisotropic layer having a plurality of regions in which the alignment states of the liquid crystal compounds are different along the thickness direction.

As will be described later, in the second embodiment, in order to manufacture an optically anisotropic layer having the above characteristics, the total content of chiral agents (total content of all chiral agents) in the composition layer is the total mass of the liquid crystal compound. With respect to , it is preferably more than 5.0% by mass.

The difference between the first embodiment and the second embodiment is mainly in the content of the chiral agent.

Hereinafter, the procedure of each process is explained in detail.

<Process 1B>

Step 1B is a step of forming a composition layer containing a chiral agent containing at least a photosensitive chiral agent whose helical organic force changes upon irradiation with light, and a liquid crystal compound having a polymerizable group. By carrying out this process, the composition layer to which the light irradiation process mentioned later is performed is formed.

The chiral agents (chiral agent A and chiral agent B) and the liquid crystal compound contained in the composition layer are as described in Step 1A.

In addition, the composition layer may contain components other than the chiral agent and the liquid crystal compound as described in Step 1A above.

In Step 1B, a chiral agent is contained in the composition layer so that a cholesteric liquid crystal phase is formed in Step 2B described later.

In the second embodiment, the total amount of chiral agents (total content of all chiral agents) in the composition layer is not particularly limited, but the total mass of the liquid crystal compound is easy to control in terms of the alignment state of the liquid crystal compound. With respect to , it is preferably more than 5.0 mass%, more preferably 5.5 mass% or more, and still more preferably 6.0 mass% or more. The upper limit is not particularly limited, but is preferably 25% by mass or less, more preferably 20% by mass or less, and still more preferably 15% by mass or less.

The content of the chiral agent A in the chiral agent is not particularly limited, but is preferably 5 to 95% by mass, relative to the total mass of the chiral agent, from the viewpoint of easy control of the alignment state of the liquid crystal compound. 90 mass % is more preferable.

The absolute value of the spiral induction force of the chiral agent in the composition layer formed in step 1B is preferably 10 μm ^-1 or more, more preferably 15 μm ^-1 or more, and still more preferably 20 μm ^-1 or more. The upper limit is not particularly limited, but is often 250 µm ^-1 or less, and is often 200 µm ^-1 or less.

In the case where two or more chiral agents are included in the composition, the absolute value of the weighted average spiral induction force of the chiral agents in the composition layer formed in step 1B is preferably within the above range.

When the spiral induction force or the absolute value of the spiral induction force of the chiral agent in the composition layer is within the above range, the liquid crystal compound in the composition is in cholesteric orientation by step 2B.

The definition of the weighted average spiral organic force is as described above.

The method for forming the composition layer in Step 1B may be the same as the method for forming the composition layer in Step 1A described above.

<Process 2B>

Step 2B is a step of heating the composition layer to align the liquid crystal compound in the composition layer to form a cholesteric liquid crystal phase. By performing this step, the liquid crystal compound in the composition layer is brought into a predetermined alignment state.

As conditions for heat treatment, optimum conditions are selected depending on the liquid crystal compound used.

Among them, the heating temperature is often 25 to 250°C, more often 40 to 150°C, and more often 50 to 130°C.

As heating time, it is 0.1 to 60 minutes in many cases, and 0.2 to 5 minutes in many cases.

<Process 3B>

Step 3B is a step in which, after step 2B, the composition layer is irradiated with light for 50 seconds or less and at 300 mJ/cm ^{2 or} less under conditions of an oxygen concentration of 1% by volume or more. Below, the mechanism of this process is demonstrated using drawing. In addition, the aspect shown in FIG. 8 corresponds to the aspect in which the liquid crystal compound forms a cholesteric liquid crystal phase.

As shown in Fig. 8, in step 3B, light is irradiated from the direction opposite to the composition layer 220 side of the substrate 10 (in the direction of the white arrow in Fig. 8) under the condition of an oxygen concentration of 1% by volume or more. . In Fig. 8, light irradiation is performed from the substrate 10 side, but it may be performed from the composition layer 220 side.

At that time, comparing the lower region 220A on the substrate 10 side of the composition layer 220 with the upper region 220B on the opposite side to the substrate 10 side, the surface of the upper region 220B is air. side, the oxygen concentration in the upper region 220B is high, and the oxygen concentration in the lower region 220A is low. Therefore, when the composition layer 220 is irradiated with light, polymerization of the liquid crystal compound easily proceeds in the lower region 220A, and the alignment state of the liquid crystal compound is fixed. In addition, chiral agent A is also present in the lower region 220A, and chiral agent A is also photosensitized, and the spiral induction force is changed. However, since the alignment state of the liquid crystal compound is fixed in the lower region 220A, even if step 4B of heat-treating the light-irradiated composition layer to be described later is performed, the alignment state of the liquid crystal compound does not change. don't

In addition, since the oxygen concentration is high in the upper region 220B, even if light is irradiated, polymerization of the liquid crystal compound is inhibited by oxygen and the polymerization does not proceed easily. And, since the chiral agent A is also present in the upper region 220B, the chiral agent A is photosensitized and the spiral induction force is changed. Therefore, when step 4B described later is performed, the alignment state of the liquid crystal compound changes according to the changed spiral induction force.

That is, by performing step 3B, fixation of the alignment state of the liquid crystal compound tends to proceed in the region (lower region) of the composition layer on the substrate side. In addition, in the region (upper region) on the opposite side of the substrate side of the composition layer, it is difficult to fix the alignment state of the liquid crystal compound, and the spiral induction force is changed depending on the photosensitized chiral agent A. .

Various conditions (oxygen concentration, irradiation time, irradiation amount, etc.) of light irradiation in Step 3B are the same as the various conditions of light irradiation in Step 3A described above.

<Process 4B>

Step 4B is a step of subjecting the composition layer to a heat treatment after step 3B at a temperature higher than that at the time of light irradiation. By carrying out this step, the alignment state of the liquid crystal compound changes in the region where the spiral induction force of the chiral agent A in the composition layer to which light irradiation has been applied has changed. More specifically, this step is a step of aligning the liquid crystal compound in the composition layer not fixed in step 3B by subjecting the composition layer after step 3B to heat treatment at a temperature higher than that during irradiation.

Below, the mechanism of this process is demonstrated using drawing.

As described above, when step 3B is performed on the composition layer 220 shown in FIG. 8, the alignment state of the liquid crystal compound is fixed in the lower region 220A, while the liquid crystal compound is polymerized in the upper region 220B. is difficult to progress, and the alignment state of the liquid crystal compound is not fixed. Also, in the upper region 220B, the spiral induction force of the chiral agent A is changing. When such a change in the spiral induction force of the chiral agent A occurs, the force to twist the liquid crystal compound in the upper region 220B is changed compared to the state before light irradiation. This point will be explained in more detail.

In the following description, a case where the composition layer 220 includes a chiral agent A whose helical direction is leftward winding and whose helical pulling force is reduced by light irradiation will be described in detail.

When light irradiation is performed in the upper region 220B in such a state, and the spiral induction force of the chiral agent A decreases with the amount of light irradiation as shown in FIG. 10, the chiral agent A in the upper region 220B The fourth spiral organic force becomes smaller.

Therefore, when heat treatment is performed on the composition layer 220 after step 3B in which such a change in spiral induction force occurs to promote reorientation of the liquid crystal compound, as shown in FIG. 9 , an upper region 220B ), the helical pitch of the cholesteric liquid crystal layer increases.

On the other hand, as described above, in the lower region 220A of the composition layer 220, the polymerization of the liquid crystal compound proceeds during step 3B and the alignment state of the liquid crystal compound is fixed, so the liquid crystal compound is not rearranged. don't

As described above, by performing step 4B, a plurality of cholesteric liquid crystal phases having different helical pitches are formed along the thickness direction of the composition layer.

In addition, in the above FIGS. 8 and 9, an embodiment using a chiral agent A, in which the spiral induction force is reduced by light irradiation, has been described, but this embodiment is not limited. For example, as the chiral agent A, a chiral agent whose helix induction force increases upon irradiation with light may be used.

In addition, in the above FIGS. 8 and 9, an embodiment using a chiral agent in which the helical direction induced as the chiral agent A is leftward winding has been described, but this embodiment is not limited thereto. For example, as the chiral agent A, a chiral agent having a right-hand winding direction may be used.

In addition, in the above FIGS. 8 and 9, an embodiment in which only one type of chiral agent A is used has been described, but this embodiment is not limited. For example, an aspect using two kinds of chiral agent A may be used, or an aspect using chiral agent A and chiral agent B may be used together.

Heat treatment is performed at a temperature higher than that at the time of light irradiation.

The difference between the temperature of the heat treatment and the temperature during light irradiation is preferably 5°C or higher, more preferably 10 to 110°C, more preferably 20 to 110°C.

The temperature of the heat treatment is higher than the temperature at the time of light irradiation, and is preferably a temperature at which the non-fixed liquid crystal compound in the composition layer is aligned, and more specifically, it is often 40 to 250 ° C., and 50 to 150 ° C. There are more cases of , more cases of more than 50 ℃ and less than 150 ℃, and especially many cases of 60 ~ 130 ℃.

As heating time, it is 0.01 to 60 minutes in many cases, and 0.03 to 5 minutes in many cases.

In addition, the absolute value of the spiral induction force of the chiral agent in the composition layer after light irradiation is not particularly limited, but the absolute value of the difference between the spiral induction force of the chiral agent in the composition layer after light irradiation and the spiral induction force before light irradiation is 0.05 μm ^-1 or more is preferable, 0.05 to 10.0 μm ^-1 is more preferable, and 0.1 to 10.0 μm ^-1 is still more preferable.

Further, when two or more chiral agents are included in the composition, the absolute value of the difference between the weighted average spiral induction force of the chiral agents in the composition layer after light irradiation and the weighted average spiral induction force before light irradiation is 0.05 μm ^-1 or more. It is preferable, 0.05 to 10.0 μm ^-1 is more preferable, and 0.1 to 10.0 μm ^-1 is still more preferable.

<Process 5B>

Step 5B is a step of performing a curing treatment on the composition layer after step 4B to form an optically anisotropic layer having a plurality of regions in which the alignment states of the liquid crystal compounds are different along the thickness direction. By carrying out this process, the alignment state of the liquid crystal compound in the composition layer is fixed, and as a result, a predetermined optically anisotropic layer is formed. Further, by carrying out this step, an optically anisotropic layer formed by fixing the cholesteric liquid crystal phase is formed, which has a plurality of regions with different helical pitches of the cholesteric liquid crystal phase along the thickness direction. In many cases, the length of the helical pitch in each formed region is constant. That is, by performing this step, the optically anisotropic layer formed by fixing the cholesteric liquid crystal phase has a plurality of regions having different helical pitches of the cholesteric liquid crystal phase along the thickness direction, and the helical pitch in each region is A certain optically anisotropic layer can be formed.

As a method of hardening treatment in step 5B, the method of hardening treatment in step 5A can be mentioned.

The thickness of the optically anisotropic layer is not particularly limited, but is preferably 0.05 to 10 μm, more preferably 0.1 to 8.0 μm, and still more preferably 0.2 to 6.0 μm.

An optically anisotropic layer obtained by fixing a cholesteric liquid crystal phase formed by the above method, wherein the optically anisotropic layer has a plurality of regions having different helical pitches of the cholesteric liquid crystal phase along the thickness direction, The selective reflection center wavelengths derived from the steric liquid crystal phase are different. For example, the optically anisotropic layer may be an optically anisotropic layer having, along the thickness direction, a region in which a cholesteric liquid crystal phase that reflects blue light is fixed and a region in which a cholesteric liquid crystal phase that reflects green light is fixed, It may be an optically anisotropic layer having, along the thickness direction, a region in which a cholesteric liquid crystal phase that reflects green light is fixed and a region in which a cholesteric liquid crystal phase that reflects red light is fixed.

In addition, in this specification, the selective reflection central wavelength is the half value transmittance expressed by the following formula when the minimum value of the transmittance in the object (member) is T _min (%): T _1/2 (% ) is the average value of the two wavelengths.

Equation for half value transmittance: T _1/2 =100-(100-T _min )÷2

Among visible light, light in a wavelength range of 420 nm to less than 500 nm is blue light (B light), light in a wavelength range of 500 nm to less than 600 nm is green light (G light), and light in a wavelength range of 600 nm to less than 700 nm is red light ( R light).

In the embodiment shown in FIG. 9 , the optically anisotropic layer has a region in which the two liquid crystal compounds are in different alignment states. You may have three or more areas. As described above, the optically anisotropic layer having three or more regions in which the alignment states of the liquid crystal compounds are different can be formed by, for example, changing the conditions of step 3B and performing the step 3B a plurality of times.

As the above optically anisotropic layer, for example, along the thickness direction, a region in which a cholesteric liquid crystal phase that reflects blue light is fixed, a region in which a cholesteric liquid crystal phase that reflects green light is fixed, and a region in which a cholesteric liquid crystal phase that reflects green light is fixed, and which reflects red light and an optically anisotropic layer having a region in which a cholesteric liquid crystal phase is fixed.

<<Third Embodiment>>

3rd Embodiment of the manufacturing method of the optically anisotropic layer of this invention has the following steps 1C-5C. As will be described later, in the third embodiment, an optically anisotropic layer having a region in which the orientation of the liquid crystal compound is aligned in an oblique or perpendicular direction with respect to the surface of the layer is fixed.

Step 1C: Step of forming a composition layer containing a photosensitive compound whose polarity is changed by light irradiation and a liquid crystal compound having a polymerizable group

Step 2C: Step of subjecting the composition layer to heat treatment to align the liquid crystal compound in the composition layer

Step 3C: After Step 2C, the composition layer is irradiated with light for 50 seconds or less and at 300 mJ/cm ² or less under the conditions of an oxygen concentration of 1% by volume or more.

Step 4C: After Step 3C, a step of subjecting the composition layer to a heat treatment at a temperature higher than that at the time of light irradiation

Step 5C: After step 4C, the composition layer is cured to form an optically anisotropic layer having a plurality of regions in which the alignment states of the liquid crystal compounds are different along the thickness direction.

In the third embodiment, as will be described later, a photosensitive compound whose polarity changes upon light irradiation is used.

Hereinafter, the procedure of each process is explained in detail.

<Process 1C>

Step 1C is a step of forming a composition layer containing a photosensitive compound whose polarity is changed by light irradiation and a liquid crystal compound having a polymerizable group. By carrying out this process, the composition layer to which the light irradiation process mentioned later is performed is formed.

The liquid crystal compound contained in the composition layer is as described in Step 1A.

In addition, the composition layer may contain other components as described in step 1A described above.

(Photosensitive compound whose polarity changes by light irradiation)

The composition layer of Step 1C contains a photosensitive compound (hereinafter also referred to as "specific photosensitive compound") whose polarity is changed by light irradiation.

A photosensitive compound whose polarity changes upon light irradiation is a compound whose polarity changes before and after light irradiation. As will be described later, when the light irradiation in Step 1C is performed on the composition layer containing such a specific photosensitive compound, the polarity of the specific compound is changed in the area on the air side in the composition layer, and when Step 4C is performed, the polarity According to the change, the alignment direction of the liquid crystal compound becomes inclined or perpendicular to the surface of the layer.

The change in the polarity of a specific photosensitive compound may be a change that makes it hydrophilic or a change that makes it hydrophobic. Among them, a hydrophilic change is preferable from the viewpoint that the alignment state of the liquid crystal compound in which the orientation direction of the liquid crystal compound is oriented obliquely or vertically with respect to the surface of the layer can be easily formed.

As the specific photosensitive compound that becomes hydrophilic by light irradiation, a compound having a group that generates a hydrophilic group by light irradiation is preferable. The type of hydrophilic group is not particularly limited, and may be any of a cationic group, an anionic group, and a nonionic group, more specifically, a carboxylic acid group, a sulfonic acid group, a phosphonic acid group, an amino group, an ammonium group, an amide group, and a thiol group. , and, a hydroxyl group may be mentioned.

It is preferable that a specific photosensitive compound has a fluorine atom or a silicon atom. When the specific photosensitive compound has the above atoms, the specific photosensitive compound tends to be unevenly distributed near the surface of the composition layer, and a desired optically anisotropic layer is easily formed.

As a specific photosensitive compound, the compound represented by Formula (X) is preferable.

[Formula 3]

In the above formula (X),

T represents an n+m valent aromatic hydrocarbon group,

Sp represents a single bond or a divalent linking group;

Hb represents a fluorine-substituted alkyl group having 4 to 30 carbon atoms;

m represents an integer of 1 to 4,

n represents an integer of 1 to 4;

A represents a group represented by the following formula (Y),

[Formula 4]

In the above formula (Y),

R ₁ to R ₅ each independently represent a hydrogen atom or a monovalent substituent;

* indicates a binding site.

In addition, in the above formula (X), when the Sp, the Hb, or the A are present in a plurality, respectively, the plurality of Sp, the plurality of Hb, or the plurality of A are the same. It can be done or it can be different.

In the formula (X), T represents an n+m valent aromatic hydrocarbon group.

The aromatic hydrocarbon group is not particularly limited as long as it is a group obtained by removing n+m hydrogen atoms from the aromatic hydrocarbon ring, but preferably has 6 to 22 carbon atoms, more preferably 6 to 14 carbon atoms, and preferably 6 to 10 carbon atoms. more preferable The aromatic hydrocarbon group is particularly preferably a benzene ring.

In addition, the aromatic hydrocarbon group may further have a substituent other than the group represented by -Sp-Hb and the group represented by -C(=O)O-A. As a substituent, an alkyl group (for example, a C1-C8 alkyl group), an alkoxy group (for example, a C1-C8 alkoxy group), a halogen atom (for example, a fluorine atom, a chlorine atom) , a bromine atom, and an iodine atom), a cyano group, and an acyloxy group (eg, acetoxy group).

In the formula (X), Sp represents a single bond or a divalent linking group, and is preferably a divalent linking group.

The divalent linking group is not particularly limited, but is a straight-chain or branched alkylene group (preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, still more preferably 1 to 6 carbon atoms), a straight-chain or branched alkylene group. A kenylene group (preferably 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms, still more preferably 2 to 6 carbon atoms), a straight-chain or branched alkynylene group (preferably 2 to 20 carbon atoms, more preferably is selected from the group consisting of 2 to 10 carbon atoms, more preferably 2 to 6 carbon atoms), or groups in which one or two or more -CH ₂ - are substituted with "divalent organic groups" shown below It is preferable that it is a linking group.

Among these divalent linking groups, an alkylene group having 1 to 10 carbon atoms in which one or two or more -CH ₂ - groups are substituted with "divalent organic groups" shown below is preferable from the viewpoint of further improving solubility.

(divalent organic group)

As said divalent organic group, -O-, -S-, -C(=O)-, -C(=O)O-, -OC(=O)-, -C(=O)S-, - SC(=O)-, -NR ₆ C(=O)-, or -C(=O)NR ₆ -. Among the above, -O-, -S-, -C(=O)-, -C(=O)O-, -OC(=O)-, -C(=O) More preferably S-, or SC(=O)-, more preferably -O-, -C(=O)-, -C(=O)O-, or OC(=O)-, and -O -, -C(=O)O-, or OC(=O)- is particularly preferred.

Moreover, said R _<6> represents a hydrogen atom or a C1-C6 alkyl group.

Moreover, when the said divalent organic group is contained in the said divalent linking group, it is preferable that the said divalent organic group is not adjacent to each other.

In the formula (X), Hb represents a fluorine-substituted alkyl group having 4 to 30 carbon atoms.

Hb preferably has 4 to 20 carbon atoms, more preferably 4 to 10 carbon atoms. Here, the fluorine-substituted alkyl group may be a perfluoroalkyl group in which all hydrogen atoms are substituted with fluorine atoms, or a fluoroalkyl group in which some of the hydrogen atoms are substituted with fluorine atoms. Further, the fluorine-substituted alkyl group may be chain, branched or cyclic, preferably chain or branched, and more preferably chain.

As a fluorine-substituted alkyl group, the structure which is a perfluoroalkyl group is preferable especially.

Preferable aspects of the group represented by -Sp-Hb in the formula (X) are exemplified below.

Also, in the following examples, * indicates a connection position with T.

(C _p F _2p+1 )-(CH ₂ ) _q -O-(CH ₂ ) _r -O-*

(C _p F _2p+1 )-(CH ₂ ) _q -C(=O)O-(CH ₂ ) _r -C(=O)O-*

(C _p F _2p+1 )-(CH ₂ ) _q -OC(=O)-(CH ₂ ) _r -C(=O)O-*

(C _p F _2p+1 )-(CH ₂ ) _q -OC(=0)-(CH ₂ ) _r -OC(=0)-*

In the group represented by the above -Sp-Hb, p is preferably 4 to 30, more preferably 4 to 20, still more preferably 4 to 10. q is preferably 0 to 6, more preferably 0 to 4, still more preferably 0 to 3. r is preferably 1 to 6, more preferably 1 to 4, still more preferably 1 to 3.

In addition, the total number of carbon atoms in parts other than the perfluoro group is preferably 10 or less.

In said Formula (X), n and m respectively independently represent the integer of 1-4.

It is preferable that n is 2 or more from the point which hydrophilization progresses more. As for m, it is preferable that it is 1-3, and it is more preferable that it is 2.

In the formula (X), A represents a group represented by the formula (Y).

Hereinafter, formula (Y) is demonstrated.

In the formula (Y), R ₁ to R ₅ each independently represent a hydrogen atom or a monovalent substituent. The monovalent substituent represented by R ₁ to R ₅ is not particularly limited.

As a monovalent substituent represented by R ₁ to R ₄ , for example, a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom), a hydroxyl group, a cyano group, substituted or non-substituted Represented by a substituted amino group (-N(R _A ) ₂ , the two R _A 's each independently represent a hydrogen atom or a monovalent organic group (as the monovalent organic group, for example, an alkyl group having 1 to 5 carbon atoms). ), an alkoxy group having 1 to 8 carbon atoms (eg, a methoxy group and an ethoxy group), an amide group having 2 to 8 carbon atoms (eg, -N(R _B )C(=O) _RC (R _B is Represents a hydrogen atom or a monovalent organic group (as a monovalent organic group, for example, an alkyl group having 1 to 5 carbon atoms), and R _C is a monovalent organic group (as a monovalent organic group, for example, 1 to 5 carbon atoms) of), or -C(=O)N(R _D ) ₂ (two R _Ds are each independently a hydrogen atom or a monovalent organic group (eg, an alkyl group having 1 to 5 carbon atoms) )), an alkoxycarbonyl group having 2 to 8 carbon atoms (eg, -C(=O)OCH ₃ ), an acyloxy group having 2 to 8 carbon atoms (eg, -OC(=O)CH ₃ ), and -Sp _A -Hb _A.

The above Sp _A and the above Hb _A have the same meaning as Sp and Hb in the above formula (X), respectively, and the preferred embodiments thereof are also the same. Further, in formula (Y), when a plurality of R ₁ to R ₄ represent -Sp _A -Hb _A , the plurality of Sp _A 's and the plurality of Hb _A 's may be the same or different, respectively. .

Among these, R ₁ to R ₄ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a cyano group, an alkoxy group, -NH ₂ , -NH(CH ₃ ), -N(CH ₃ ) ₂ , - C(=O)OCH ₃ , -OC(=O)CH ₃ , -NHC(=O)CH ₃ , -N(CH ₃ )C(=O)CH ₃ , or -Sp _A -Hb _A is preferred. do.

In particular, from the viewpoint of accelerating the decomposition rate of the compound represented by formula (X) by exposure to more rapid progress of hydrophilicity and/or higher orientation, said R ₁ to R ₄ are each independently —OCH ₃ or Sp _A -Hb _A is more preferable. In the case of -OCH ₃ , since the structure contains ether oxygen (particularly, the position bonding to the benzene ring in formula (Y) is ether oxygen), the decomposition rate of the compound represented by formula (X) by exposure to light is It becomes faster and there is a tendency for hydrophilization to proceed more. On the other hand, in the case of -Sp _A -Hb _A , the orientation tends to be higher due to the presence of Hb _A. In addition, when Sp _A contains ether oxygen in its structure (in particular, the end of Sp _A on the side opposite to the side bonded to Hb _A (in other words, the end of the side bonded to the benzene ring of formula (Y)) ether. When oxygen is included), the effect of increasing the decomposition rate is obtained, similarly to the above -OCH ₃ .

In addition, in that the decomposition rate of the compound represented by formula (X) by exposure is further accelerated and hydrophilization further progresses, at least two of the above R ₁ to R ₄ are each independently -OCH ₃ or Sp _B - It is preferably Hb _B , and more preferably R ₂ and R ₃ are each independently -OCH ₃ or Sp _B -Hb _B.

Here, Sp _B represents an alkylene group having 1 to 10 carbon atoms in which -CH ₂ - is substituted with -O-. Among them, as described above, when ether oxygen is contained in the end of Sp _B on the side opposite to the side bonded to Hb _B (in other words, the end on the side connected to the benzene ring of formula (Y)), the decomposition rate is increased. The effect of accelerating is obtained more remarkably, and hydrophilization further advances. Moreover, when _-CH2- in the said alkylene group is substituted by several -O-, it is preferable that -O- is not adjacent. The alkylene group preferably has 1 to 7 carbon atoms, more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms. Further, the alkylene group may be either straight-chain or branched, but is preferably straight-chain.

Said Hb _B represents a C4-C30 fluorine-substituted alkyl group. About the suitable aspect of the said Hb _B , it is the same as that of Hb of Formula (X) mentioned above.

Further, in formula (Y), when a plurality of R ₁ to R ₄ represent -Sp _B -Hb _B , the plurality of Sp _Bs and the plurality of Hb _Bs may be the same or different, respectively. .

Among them, at least two of the above-mentioned R ₁ to R ₄ are -Sp _B -Hb _B from the viewpoint that the decomposition rate of the compound represented by formula (X) by exposure is accelerated, the hydrophilization further proceeds, and the orientation is further improved. is preferable, and it is more preferable that both R ₂ and R ₃ are -Sp _B -Hb _B. In particular, as the above _{-SpB -HbB} , a structure represented by the following formula (Z) is preferable.

Formula (Z) (C _p F _2p+1 )-(CH ₂ ) _q -O-(CH ₂ ) _r -O-*

In formula (Z), p is preferably 4 to 30, more preferably 4 to 20, still more preferably 4 to 10. q is preferably 0 to 5, more preferably 0 to 4, still more preferably 0 to 3. r is preferably 1 to 5, more preferably 1 to 4, still more preferably 1 to 3.

In the formula (Y), R ₅ is preferably a hydrogen atom, a methyl group, an ethyl group, or an aromatic group.

The aromatic group is not particularly limited, but is preferably 6 to 14 carbon atoms, more preferably 6 to 10 carbon atoms, and still more preferably a phenyl group.

R ₅ , among others, is preferably a methyl group, an ethyl group, or an aromatic group, and more preferably an ethyl group or an aromatic group, from the viewpoint of accelerating the decomposition rate of the compound represented by formula (X) by exposure to light to further promote hydrophilicity; Aromatic groups are more preferred.

In the above formula (Y), * represents a bonding site with C(=O)O- in the above formula (X).

The compound represented by the formula (X) may have a symmetrical molecular structure or may not have symmetrical properties. Symmetry as used herein means that it corresponds to any one of point symmetry, line symmetry, and rotational symmetry, and asymmetry means that it does not correspond to any of point symmetry, line symmetry, and rotational symmetry.

Further, in the compound represented by the formula (X), when a plurality of Sp, Hb, or A are present, a plurality of Sp, a plurality of Hb, or a plurality of A are present. Each other may be the same or different.

The content of the specific photosensitive compound in the composition layer can be appropriately set according to the characteristics (for example, retardation or wavelength dispersion) of the optically anisotropic layer to be formed.

Among them, the content of the specific photosensitive compound is preferably 0.01 to 10% by mass, and more preferably 0.05 to 5% by mass, based on the total mass of the liquid crystal compound, from the viewpoint that an optically anisotropic layer having a predetermined structure is more easily formed. .

In Step 1A, a composition layer containing the components described above is formed, but the procedure is not particularly limited. For example, a method in which a composition containing the above-described specific photosensitive compound and a liquid crystal compound having a polymerizable group is applied onto a substrate and, if necessary, dried (hereinafter, simply referred to as "application method"), and , a method of forming a separate composition layer and transferring it onto a substrate. Among them, the coating method is preferable from the viewpoint of productivity.

Hereinafter, the application method is explained in detail.

In the composition used in the application method, the above-described specific photosensitive compound, liquid crystal compound having a polymerizable group, and other components used as necessary (eg, polymerization initiator, polymerizable monomer, surfactant, and polymer) etc.) are included.

The content of each component in the composition is preferably adjusted so as to be the content of each component in the composition layer described above.

The application method is not particularly limited, and examples thereof include a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method.

Further, if necessary, a treatment of drying the coating film applied on the substrate may be performed after application of the composition. By performing the drying treatment, the solvent can be removed from the coating film.

The film thickness of the coating film is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, and still more preferably 0.5 to 10 μm.

<Process 2C>

Step 2C is a step of subjecting the composition layer to heat treatment to orient the liquid crystal compound in the composition layer. By performing this step, the liquid crystal compound in the composition layer is brought into a predetermined alignment state. In addition, as shown in FIG. 11 described later, the liquid crystal compound is homogeneously aligned in the composition by, for example, Step 2C.

As conditions for heat treatment, optimum conditions are selected depending on the liquid crystal compound used.

Among them, the heating temperature is often 25 to 250°C, more often 40 to 150°C, and more often 50 to 130°C.

As heating time, it is 0.1 to 60 minutes in many cases, and 0.2 to 5 minutes in many cases.

<Process 3C>

Step 3C is a step of irradiating the composition layer with light for 50 seconds or less and at 300 mJ/cm ² or less under conditions of an oxygen concentration of 1 vol% or more after step 2C. Below, the mechanism of this process is demonstrated using drawing. In addition, below, the case where the composition layer contains the compound which becomes hydrophilic by light irradiation is demonstrated as an example. In FIG. 11 , in the composition layer, the liquid crystal compound (LC) is oriented homogeneously.

As shown in Fig. 11, in Step 3C, light is irradiated from the direction opposite to the composition layer 320 side of the substrate 10 (direction of the white arrow in Fig. 11) under the condition of an oxygen concentration of 1% by volume or more. . In Fig. 11, light irradiation is performed from the substrate 10 side, but it may be performed from the composition layer 320 side.

At that time, comparing the lower region 320A on the substrate 10 side of the composition layer 320 with the upper region 320B on the opposite side to the substrate 10 side, the surface of the upper region 320B is air. side, the oxygen concentration in the upper region 320B is high, and the oxygen concentration in the lower region 320A is low. Therefore, when the composition layer 320 is irradiated with light, polymerization of the liquid crystal compound tends to proceed in the lower region 320A, and the alignment state of the liquid crystal compound is fixed. Also in the lower region 320A, a specific photosensitive compound is present, and the specific photosensitive compound is also photosensitized and hydrophilization proceeds. However, since the alignment state of the liquid crystal compound is fixed in the lower region 320A, even if step 4C of heating the light-irradiated composition layer to be described later is performed, the alignment state of the liquid crystal compound does not change. don't

In addition, since the oxygen concentration is high in the upper region 320B, polymerization of the liquid crystal compound is inhibited by oxygen even when light is irradiated, and thus polymerization does not proceed easily. And since the specific photosensitive compound exists also in the upper area|region 320B, the specific photosensitive compound is photosensitive and hydrophilization progresses. Therefore, when Step 4C described later is performed, the alignment state of the liquid crystal compound changes under the influence of the changed polarity.

That is, by performing step 3C, fixation of the alignment state of the liquid crystal compound tends to proceed in the region (lower region) of the composition layer on the substrate side. In addition, in the region (upper region) of the composition layer on the opposite side of the substrate side, the alignment state of the liquid crystal compound is difficult to be fixed, and the polarity is changed depending on the specific photosensitive compound that is exposed to light.

Various conditions (oxygen concentration, irradiation time, irradiation amount, etc.) of light irradiation in Step 3C are the same as the various conditions of light irradiation in Step 3A described above.

<Process 4C>

Step 4C is a step of subjecting the composition layer to a heat treatment after Step 3C at a temperature higher than that at the time of light irradiation. By carrying out this process, the orientation state of the liquid crystal compound changes in the area|region where the polarity changed by the specific photosensitive compound in the composition layer to which light irradiation was performed. More specifically, this step is a step of aligning the liquid crystal compound in the composition layer that is not fixed in step 3C by subjecting the composition layer after step 3C to heat treatment at a temperature higher than that during irradiation.

Below, the mechanism of this process is demonstrated using drawing.

As described above, when step 3C is performed on the composition layer 320 shown in FIG. 11, the alignment state of the liquid crystal compound is fixed in the lower region 320A, while the liquid crystal compound is polymerized in the upper region 320B. is difficult to progress, and the alignment state of the liquid crystal compound is not fixed. Further, in the upper region 320B, a specific photosensitive compound is photosensitized and becomes hydrophilic. When such a polarity change occurs, the alignment direction of the liquid crystal compound in the upper region 320B is affected compared to the state before light irradiation. This point will be explained in more detail. In addition, as described above, a case in which the composition layer contains a specific photosensitive compound that becomes hydrophilic by light irradiation will be described below as an example.

When the composition layer contains a specific photosensitive compound that becomes hydrophilic by light irradiation, as shown in FIG. 12 , when step 4C is performed, the liquid crystal compound is vertically aligned (homeotropic alignment) in the upper region 320B. do. In particular, when a specific photosensitive compound exists near the surface of the composition layer, the liquid crystal compound tends to vertically align.

On the other hand, as described above, in the lower region 320A of the composition layer 320, the polymerization of the liquid crystal compound proceeds during step 3C and the alignment state of the liquid crystal compound is fixed, so the liquid crystal compound is not rearranged. don't

As described above, by carrying out Step 4C, a region containing a liquid crystal compound whose alignment direction is oriented obliquely or perpendicularly to the surface of the layer is formed.

In addition, in the said FIG. 11, although the aspect in which the liquid crystal compound is vertically aligned was demonstrated, it is not limited to this aspect. For example, the aspect in which the liquid crystal compound is aligning obliquely may be sufficient.

Heat treatment is performed at a temperature higher than that at the time of light irradiation.

The difference between the temperature of the heat treatment and the temperature during light irradiation is preferably 5°C or higher, more preferably 10 to 110°C, more preferably 20 to 110°C.

The temperature of the heat treatment is higher than the temperature at the time of light irradiation, and is preferably a temperature at which the non-fixed liquid crystal compound in the composition layer is aligned, and more specifically, it is often 40 to 250 ° C., and 50 to 150 ° C. There are more cases of , more cases of more than 50 ℃ and less than 150 ℃, and especially many cases of 60 ~ 130 ℃.

As heating time, it is 0.01 to 60 minutes in many cases, and 0.03 to 5 minutes in many cases.

<Process 5C>

Step 5C is a step of forming an optically anisotropic layer having a plurality of regions having different orientation states of liquid crystal compounds along the thickness direction by subjecting the composition layer to a curing treatment after step 4C. By carrying out this process, the alignment state of the liquid crystal compound in the composition layer is fixed, and as a result, a predetermined optically anisotropic layer is formed. Furthermore, by performing this step, an optically anisotropic layer having a plurality of regions having different inclination angles of the orientation direction of the liquid crystal compound with respect to the layer surface along the thickness direction is formed. In particular, by carrying out this step, along the thickness direction, a region obtained by fixing the alignment state of the liquid crystal compound vertically aligned (homeotropic alignment) or tilted alignment, and the alignment state of the liquid crystal compound horizontally aligned (homogeneous alignment) An optically anisotropic layer having a region formed by fixing can be formed.

As a method of hardening treatment in step 5C, the method of hardening treatment in step 5A can be mentioned.

The thickness of the optically anisotropic layer is not particularly limited, but is preferably 0.05 to 10 μm, more preferably 0.1 to 8.0 μm, and still more preferably 0.2 to 6.0 μm.

The optical properties in the optically anisotropic layer in the third embodiment are not particularly limited, and optimum values are selected depending on the application. Hereinafter, as an example, a first region formed by fixing the orientation state of the homeotropically aligned liquid crystal compound produced by the above-described procedure, and a second region obtained by fixing the orientation state of the homogeneously aligned liquid crystal compound, The case of the optically anisotropic layer along the thickness direction will be described in detail.

When the thickness of the first region of the optically anisotropic layer is Δn1 and the in-plane refractive index anisotropy of the first region measured at d1 and a wavelength of 550 nm, the optically anisotropic layer can be suitably applied to a circular polarizing plate and a liquid crystal display device It is preferable that the first region satisfies the following formula (1C-1) from the viewpoint of being able to reduce light leakage in the oblique direction when applied as an optical compensating plate of .

Equation (1C-1) 0nm≤Δn1d1≤30nm

Among them, it is more preferable to satisfy the formula (1C-2).

Equation (1C-2) 0nm≤Δn1d1≤20nm

The retardation in the thickness direction at a wavelength of 550 nm in the first region of the optically anisotropic layer is preferably -150 to -20 nm, and more preferably -120 to -20 nm.

In addition, when the thickness of the second region of the optically anisotropic layer is d2 and the in-plane refractive index anisotropy of the second region measured at a wavelength of 550 nm is Δn2, the optically anisotropic layer can be suitably applied to a circular polarizing plate or a liquid crystal From the viewpoint of being suitably applicable to an optical compensating plate of a display device, the second region preferably satisfies the following expression (2C-1). That is, the in-plane retardation in the second region at a wavelength of 550 nm is preferably 100 to 180 nm.

Equation (2C-1) 100nm≤Δn2d2≤180nm

Among them, it is more preferable to satisfy the formula (2C-2).

Equation (2C-2) 110nm≤Δn2d2≤170nm

Further, the refractive index anisotropy Δn2 means the refractive index anisotropy of the first region.

The optically anisotropic layer in the third embodiment preferably exhibits reverse wavelength dispersion.

That is, the in-plane retardation Re (450) measured at a wavelength of 450 nm of the optical anisotropic layer, the in-plane retardation Re (550) measured at a wavelength of 550 nm of the optical anisotropic layer, and the in-plane retardation measured at a wavelength of 650 nm of the optical anisotropic layer Re (650), which is retardation, preferably has a relationship of Re (450) ≤ Re (550) ≤ Re (650).

The optical properties of the optically anisotropic layer in the third embodiment are not particularly limited, but it is preferable to function as a λ/4 plate or as an optical compensation plate of a liquid crystal display device.

The λ/4 plate is a plate having a function of converting linearly polarized light of a predetermined specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light), and the in-plane retardation Re(λ) at a specific wavelength λnm is Re It refers to a plate (optically anisotropic layer) that satisfies (λ)=λ/4.

This formula only needs to be achieved at any wavelength in the visible light range (eg, 550 nm), but the in-plane retardation Re(550) at a wavelength of 550 nm satisfies the relationship of 100 nm ≤ Re (550) ≤ 180 nm It is desirable to do

<<Fourth Embodiment>>

The fourth embodiment of the optically anisotropic layer manufacturing method of the present invention includes the following steps 1D to 5D. As will be described later, in the fourth embodiment, a region obtained by fixing an alignment state in which the liquid crystal compound is aligned (for example, a horizontal alignment state), and a state in which the liquid crystal compound is not aligned (isotropic phase of the liquid crystal compound) ) is formed along the thickness direction.

Step 1D: Forming a composition layer containing a liquid crystal compound having a polymerizable group

Step 2D: Step of subjecting the composition layer to heat treatment to align the liquid crystal compound in the composition layer

Step 3D: After step 2D, the composition layer is irradiated with light for 50 seconds or less under conditions of an oxygen concentration of 1% by volume or more, and further, a step of performing light irradiation at 300 mJ/cm ^{2 or} less.

Step 4D: After Step 3D, the composition layer is subjected to heat treatment at a temperature higher than that at the time of light irradiation and higher than that at which the liquid crystal compound becomes isotropic.

Step 5D: After step 4D, the composition layer is cured to form an optically anisotropic layer having a plurality of regions in which the alignment states of the liquid crystal compounds are different along the thickness direction.

Hereinafter, the procedure of each process is explained in detail.

<Process 1D>

Step 1D is a step of forming a composition layer containing a liquid crystal compound having a polymerizable group. By carrying out this process, the composition layer to which the light irradiation process mentioned later is performed is formed.

The liquid crystal compound contained in the composition layer is as described in Step 1A.

In addition, the composition layer may contain components other than the liquid crystal compound as described in step 1A described above.

In Step 1A, a composition layer containing the components described above is formed, but the procedure is not particularly limited. For example, a method of applying a composition containing a liquid crystal compound having a polymerizable group as described above on a substrate and, if necessary, performing a drying treatment (hereinafter, simply referred to as a "coating method"), and a separate composition layer. A method of forming and transferring onto a substrate may be mentioned. Among them, the application method is preferable from the viewpoint of productivity.

Hereinafter, the application method is explained in detail.

The composition used in the application method includes the above-described liquid crystal compound having a polymerizable group and other components (eg, polymerization initiator, polymerizable monomer, surfactant, and polymer) used as necessary. included

The content of each component in the composition is preferably adjusted so as to be the content of each component in the composition layer described above.

The application method is not particularly limited, and examples thereof include a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method.

Further, if necessary, a treatment of drying the coating film applied on the substrate may be performed after application of the composition. By performing the drying treatment, the solvent can be removed from the coating film.

The film thickness of the coating film is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, and still more preferably 0.5 to 10 μm.

<Process 2D>

Step 2D is a step of subjecting the composition layer to heat treatment to align the liquid crystal compound in the composition layer. By performing this step, the liquid crystal compound in the composition layer is brought into a predetermined alignment state. In addition, as shown in FIG. 13 described later, the liquid crystal compound is homogeneously aligned in the composition by, for example, Step 2D.

As conditions for heat treatment, optimum conditions are selected depending on the liquid crystal compound used.

Among them, the heating temperature is often 25 to 250°C, more often 40 to 150°C, and more often 50 to 130°C.

As heating time, it is 0.1 to 60 minutes in many cases, and 0.2 to 5 minutes in many cases.

<Process 3D>

Step 3D is a step in which, after step 2D, the composition layer is irradiated with light for 50 seconds or less and at 300 mJ/cm ^{2 or} less under conditions of an oxygen concentration of 1% by volume or more. Below, the mechanism of this process is demonstrated using drawing. In FIG. 13 , in the composition layer, the liquid crystal compound (LC) is oriented homogeneously.

As shown in FIG. 13, in step 3D, light is irradiated from the direction opposite to the composition layer 420 side of the substrate 10 (the direction of the white arrow in FIG. 13) under the condition of an oxygen concentration of 1% by volume or more. . In Fig. 13, light irradiation is performed from the substrate 10 side, but it may be performed from the composition layer 420 side.

At that time, comparing the lower region 420A on the substrate 10 side of the composition layer 420 with the upper region 420B on the opposite side to the substrate 10 side, the surface of the upper region 420B is air. side, the oxygen concentration in the upper region 420B is high, and the oxygen concentration in the lower region 420A is low. Therefore, when the composition layer 420 is irradiated with light, polymerization of the liquid crystal compound easily proceeds in the lower region 420A, and the alignment state of the liquid crystal compound is fixed. Therefore, even if step 4D of heat-treating the light-irradiated composition layer, which will be described later, is performed, the alignment state of the liquid crystal compound does not change.

In addition, since the oxygen concentration is high in the upper region 420B, polymerization of the liquid crystal compound is inhibited by oxygen even when light is irradiated, and thus polymerization does not proceed easily. Therefore, when Step 4D described later is performed, the alignment state of the liquid crystal compound changes.

That is, by performing step 3D, fixation of the alignment state of the liquid crystal compound tends to proceed in the region (lower region) on the substrate side of the composition layer. In addition, in the region (upper region) of the composition layer opposite to the substrate side, it is difficult to fix the orientation state of the liquid crystal compound, and the orientation state of the liquid crystal compound is changed by Step 4D described later.

Various conditions (oxygen concentration, irradiation time, irradiation amount, etc.) of light irradiation in Step 3D are the same as the various conditions of light irradiation in Step 3A described above.

<Process 4D>

Step 4D is a step of heating the composition layer after step 3D at a temperature higher than that at the time of light irradiation and higher than that at which the liquid crystal compound becomes isotropic. By carrying out this process, in the upper area|region where the orientation state of the liquid crystal compound in a composition layer is not fixed, the liquid crystal compound shows an isotropic phase.

Below, the mechanism of this process is demonstrated using drawing.

As described above, when the step 3D is performed on the composition layer 420 shown in FIG. 13, the alignment state of the liquid crystal compound is fixed in the lower region 420A, while the liquid crystal compound is polymerized in the upper region 420B. is difficult to progress, and the alignment state of the liquid crystal compound is not fixed.

Therefore, when step 4D is performed, as shown in FIG. 14 , since the polymerization of the liquid crystal compound does not proceed in the upper region 420B, the alignment state of the liquid crystal compound is collapsed, resulting in an isotropic phase.

On the other hand, as described above, in the lower region 420A of the composition layer 420, the polymerization of the liquid crystal compound proceeds during the step 3D and the orientation state of the liquid crystal compound is fixed, so the liquid crystal compound is not rearranged. don't

As described above, by performing step 4D, a region formed by fixing the alignment state (for example, horizontal alignment state) of the liquid crystal compound along the thickness direction, and a state in which the liquid crystal compound is not aligned (isotropic phase of the liquid crystal compound) ) is formed to form an optically anisotropic layer having a region formed by fixing.

The heat treatment is performed at a temperature higher than the temperature at the time of light irradiation and higher than the temperature at which the liquid crystal compound becomes an isotropic phase.

The difference between the temperature of the heat treatment and the temperature during light irradiation is preferably 5°C or higher, more preferably 10 to 110°C, more preferably 20 to 110°C.

The temperature of the heat treatment is higher than the temperature at the time of light irradiation, and is preferably a temperature at which the non-fixed liquid crystal compound in the composition layer is in an isotropic phase, more specifically, it is often 40 to 250 ° C., and 50 to 250 ° C. There are more cases of 150 ° C, more cases of more than 50 ° C and less than 150 ° C, and especially many cases of 60 ~ 130 ° C.

As heating time, it is 0.01 to 60 minutes in many cases, and 0.03 to 5 minutes in many cases.

<Process 5D>

Step 5D is a step of performing a curing treatment on the composition layer after step 4D to form an optically anisotropic layer having a plurality of regions in which the alignment states of the liquid crystal compounds are different along the thickness direction. By carrying out this process, the alignment state of the liquid crystal compound in the composition layer is fixed, and as a result, a predetermined optically anisotropic layer is formed.

As a method of hardening treatment in step 5D, the method of hardening treatment in step 5A can be mentioned.

The thickness of the optically anisotropic layer is not particularly limited, but is preferably 0.05 to 10 μm, more preferably 0.1 to 8.0 μm, and still more preferably 0.2 to 6.0 μm.

13 and 14, an optically anisotropic layer having a region formed by fixing the alignment state of the horizontally aligned liquid crystal compound and a region formed by fixing the state in which the liquid crystal compound exhibits an isotropic phase along the thickness direction. Although the embodiment has been described, it is not limited to this embodiment as long as a region formed by fixing the state in which the liquid crystal compound exhibits an isotropic phase is included.

For example, as the orientation state of the liquid crystal compound, when the liquid crystal compound is a rod-shaped liquid crystal compound, the orientation state is, for example, nematic orientation (state in which a nematic phase is formed), smectic orientation (formation of a smectic phase), state), cholesteric orientation (state in which cholesteric phase is formed), and hybrid orientation. When the liquid crystal compound is a discotic liquid crystal compound, examples of the alignment state include nematic alignment, columnar alignment (a state in which a columnar phase is formed), and cholesteric alignment.

More specifically, an optically anisotropic layer having a region formed by fixing the alignment state of vertically aligned liquid crystal compounds and a region obtained by fixing the state in which the liquid crystal compound exhibits an isotropic phase may be formed along the thickness direction. Further, along the thickness direction, an optically anisotropic layer having a region formed by fixing a cholesteric liquid crystal phase formed using a liquid crystal compound and a region formed by fixing a state in which the liquid crystal compound exhibits an isotropic phase may be formed.

The optical properties of the optically anisotropic layer in the fourth embodiment are not particularly limited, but it is preferable to function as a λ/4 plate.

The λ/4 plate is a plate having a function of converting linearly polarized light of a predetermined specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light), and the in-plane retardation Re(λ) at a specific wavelength λnm is Re It refers to a plate (optically anisotropic layer) that satisfies (λ)=λ/4.

This formula only needs to be achieved at any wavelength in the visible light range (eg 550 nm), but the in-plane retardation Re(550) at a wavelength of 550 nm satisfies the relationship of 110 nm ≤ Re (550) ≤ 180 nm It is desirable to do

<<Use>>

The optically anisotropic layer can be combined with various members.

For example, the optically anisotropic layer may be combined with another optically anisotropic layer. That is, as shown in FIG. 15 , a laminate 24 including a substrate 10, an optically anisotropic layer 20 manufactured by the above-described manufacturing method, and another optically anisotropic layer 22 may be produced. . In addition, although the laminate 24 described in FIG. 15 includes the substrate 10, the substrate does not have to be included in the laminate.

The other optically anisotropic layer is not particularly limited, and examples thereof include an A plate (positive A plate and negative A plate) and a C plate (positive C plate and negative C plate). Among them, the C plate is preferable because it is easy to apply to various uses (for example, a circular polarizing plate) described later.

The range of the absolute value of the retardation in the thickness direction at a wavelength of 550 nm of the C plate is not particularly limited, but is preferably 5 to 300 nm and more preferably 10 to 200 nm.

In addition, in this specification, A plate and C plate are defined as follows.

There are two types of A plate, a positive A plate (positive A plate) and a negative A plate (negative A plate), and the refractive index in the slow axis direction within the film plane (the direction in which the refractive index within the plane becomes the maximum) is nx, When the refractive index in the direction perpendicular to the in-plane slow axis and the in-plane direction is ny and the refractive index in the thickness direction is nz, the positive A plate satisfies the relationship of equation (A1), and the negative A plate has the relationship of equation (A2) is to satisfy In addition, the positive A plate shows a positive Rth value, and the negative A plate shows a negative Rth value.

Equation (A1) nx>ny≒nz

Equation (A2) ny<nx≒nz

In addition, the said "≒" includes not only the case where both are completely the same, but also the case where both are substantially the same. “Substantially the same” means “ny≒nz” also when (ny-nz)×d (where d is the thickness of the film) is -10 to 10 nm, preferably -5 to 5 nm, for example. , and the case where (nx-nz)×d is -10 to 10 nm, preferably -5 to 5 nm, is also included in "nx ≈ nz".

There are two types of C plate, positive C plate (positive C plate) and negative C plate (negative C plate), the positive C plate satisfies the relationship of formula (C1), and the negative C plate is the formula (C2 ) to satisfy the relationship. In addition, the positive C plate shows a negative Rth value, and the negative C plate shows a positive Rth value.

Equation (C1) nz>nx≒ny

Equation (C2) nz<nx≒ny

In addition, the said "≒" includes not only the case where both are completely the same, but also the case where both are substantially the same. “Substantially the same” means, for example, that “nx≒ny” includes the case where (nx−ny)×d (where d is the film thickness) is 0 to 10 nm, preferably 0 to 5 nm. do.

The manufacturing method of the laminate is not particularly limited, and a known method may be used. For example, a method of obtaining a laminate by laminating an optically anisotropic layer obtained by the production method of the present invention and another optically anisotropic layer (for example, C plate) is exemplified. As the lamination method, another optically anisotropic layer produced separately may be bonded onto the optically anisotropic layer obtained by the production method of the present invention, and another optically anisotropic layer is formed on the optically anisotropic layer obtained by the production method of the present invention A composition for the above may be applied to form another optically anisotropic layer.

Moreover, you may combine the optically anisotropic layer obtained by the manufacturing method of this invention with a polarizer. That is, as shown in FIG. 16 , the optically anisotropic layer 28 with a polarizer including the substrate 10, the optically anisotropic layer 20 manufactured by the above-described manufacturing method, and the polarizer 26 may be produced. . In FIG. 16 , the polarizer 26 is disposed on the substrate 10, but this aspect is not limited, and the polarizer 26 may be disposed on the optically anisotropic layer 20.

Moreover, although the optically anisotropic layer 28 with a polarizer described in FIG. 16 contains the board|substrate 10, the board|substrate does not need to be contained in the optically anisotropic layer with a polarizer.

The positional relationship at the time of laminating the optically anisotropic layer and the polarizer is not particularly limited, but the optically anisotropic layer fixes the alignment state of the liquid crystal compound torsionally aligned along the helical axis extending along the thickness direction. When the second region formed by fixing the alignment state of the aligned liquid crystal compound is provided along the thickness direction, the absolute value of the angle between the in-plane slow axis of the second region and the absorption axis of the polarizer is such that the optically anisotropic layer is suitable for a circular polarizing plate or the like. In view of the fact that it can be applied, it is preferably 5 to 25 °, and more preferably 10 to 20 °.

In addition, when the angle between the in-plane slow axis of the second region and the absorption axis of the polarizer is negative, it is preferable that the twist angle of the liquid crystal compound in the first region is also negative, and the absorption of the polarizer and the in-plane slow axis of the second region is negative. When the angle formed by the axis is positive, it is preferable that the twist angle of the liquid crystal compound in the first region is also positive.

In addition, the case where the angle formed by the in-plane slow axis and the polarizer is negative means the case where the rotation angle of the in-plane slow axis with respect to the absorption axis of the polarizer is clockwise when viewed from the polarizer side, and the in-plane slow axis and the polarizer The case where the angle formed by is positive means the case where the rotation angle of the in-plane slow axis is counterclockwise with respect to the absorption axis of the polarizer when viewed from the polarizer side.

In addition, with respect to the twist angle of the liquid crystal compound, when the orientation direction of the liquid crystal compound on the inner side is clockwise (right rotation) with respect to the orientation direction of the liquid crystal compound on the surface side (front side) as a reference, counterclockwise ( Left rotation) is expressed as a quantity.

The polarizer may be a member having a function of converting natural light into specific linearly polarized light, and examples thereof include an absorption type polarizer.

The type of polarizer is not particularly limited, and a commonly used polarizer can be used, and examples thereof include an iodine-based polarizer, a dye-based polarizer using a dichroic dye, and a polyene-based polarizer. An iodine-type polarizer and a dye-type polarizer are generally produced by adsorbing iodine or a dichroic dye to polyvinyl alcohol and extending it.

Moreover, a protective film may be arrange|positioned on the single side|surface or both surfaces of a polarizer.

The manufacturing method of the said optically anisotropic layer with a polarizer is not specifically limited, A well-known method is mentioned. For example, the method of laminating|stacking the optically anisotropic layer obtained by the manufacturing method of this invention, and a polarizer, and obtaining the optically anisotropic layer with a polarizer is mentioned.

In addition, although the aspect of laminating|stacking an optically anisotropic layer and a polarizer was demonstrated above, in this invention, you may manufacture a laminated body with a polarizer by laminating the above-mentioned laminated body and a polarizer.

The optically anisotropic layer can be applied to various uses. For example, the optically anisotropic layer can be suitably applied to a circular polarizing plate, and the optically anisotropic layer with a polarizer can also be used as a circular polarizing plate.

A circularly polarizing plate having the above configuration is suitable for antireflection applications in image display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), electroluminescence displays (ELDs), and cathode tube displays (CRTs). Thus, the contrast ratio of display light can be improved.

For example, an aspect in which the circular polarizing plate of the present invention is used on the light extraction surface side of an organic EL display device is exemplified. In this case, external light becomes linearly polarized light by the polarizing film and then becomes circularly polarized light by passing through the optically anisotropic layer. When this is reflected from the metal electrode, the circularly polarized light state is reversed, and when it passes through the optically anisotropic layer again, it becomes linearly polarized light tilted by 90° from the time of incidence, and reaches the polarizing film and is absorbed. As a result, the influence of external light can be suppressed.

Especially, it is preferable that the optically anisotropic layer with a polarizer or the laminated body with a polarizer mentioned above is applied to an organic electroluminescent display device. That is, it is preferable that the optically anisotropic layer with a polarizer or the laminated body with a polarizer is disposed on an organic EL panel of an organic EL display device and applied to antireflection applications.

An organic EL panel is a member in which a light emitting layer or a plurality of organic compound thin films including a light emitting layer are formed between a pair of electrodes of an anode and a cathode, and in addition to the light emitting layer, a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, and a protective layer It may have layers or the like, and each layer may have a different function. Various materials can be used for the formation of each layer.

The optically anisotropic layer can also be suitably applied to an optical compensation plate of a liquid crystal display device, and the optically anisotropic layer with a polarizer can also be used as an optical compensation plate of a liquid crystal display device.

The liquid crystal cell used in the liquid crystal display device is VA (Vertical Alignment) mode, OCB (Optically Compensated Bend) mode, IPS (In-Plane-Switching) mode, FFS (Fringe-Field-Switching) mode, or TN (Twisted Nematic) mode is preferred, but not limited thereto.

When the optically anisotropic layer with a polarizer is used as an optical compensating plate of an IPS mode or FFS mode liquid crystal display device, the optically anisotropic layer is homogeneously aligned (horizontal alignment) as shown in FIG. 12. Alignment state of the liquid crystal compound It is preferable to have a region formed by fixing and a region formed by fixing the alignment state of the homeotropically aligned (vertical alignment) liquid crystal compound. In this case, it is preferable that the angle formed by the in-plane slow axis of the region formed by fixing the alignment state of the liquid crystal compound subjected to homogeneous alignment (horizontal alignment) and the absorption axis of the polarizer is orthogonal or parallel. Specifically, homogeneous alignment (Horizontal alignment) It is more preferable that the angle formed by the in-plane slow axis of the region formed by fixing the alignment state of the liquid crystal compound and the absorption axis of the polarizer is 0 to 5° or 85 to 95°.

Here, the "in-plane slow axis" of the region formed by fixing the alignment state of the homogeneous (horizontal alignment) liquid crystal compound is in the plane of the region formed by fixing the alignment state of the homogeneous (horizontal alignment) liquid crystal compound. means the direction in which the refractive index is greatest, and the "absorption axis" of the polarizer means the direction in which the absorbance is highest.

In addition, when the optically anisotropic layer with a polarizer is used as an optical compensation plate of an IPS mode or FFS mode liquid crystal display device, a polarizer, a region formed by fixing the alignment state of a homeotropically aligned (vertical alignment) liquid crystal compound, a homo A region formed by fixing the alignment state of liquid crystal compounds subjected to genius alignment (horizontal alignment), and a region formed by fixing the alignment state of liquid crystal compounds arranged in the order of liquid crystal cells or polarizers and homogeneous alignment (horizontal alignment) , a region formed by fixing the alignment state of the homeotropically aligned (vertical alignment) liquid crystal compound, and a liquid crystal cell are preferably arranged in this order.

Example

The features of the present invention will be described in more detail below with reference to Examples and Comparative Examples. Materials, amount of use, ratio, process content, process procedure, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

<Example 1>

(Production of cellulose acylate film (substrate))

The following composition was put into a mixing tank, stirred, and further heated at 90°C for 10 minutes. Then, the obtained composition was filtered with a filter paper having an average pore diameter of 34 µm and a sintered metal filter having an average pore diameter of 10 µm to prepare dope. The solid content concentration of dope is 23.5 mass %, the addition amount of a plasticizer is a ratio with respect to cellulose acylate, and the solvent of dope is methylene chloride / methanol / butanol = 81/18/1 (mass ratio).

-------------------------------------------------- -----------

Cellulose acylate dope

-------------------------------------------------- -----------

Cellulose acylate (acetyl substitution degree 2.86, viscosity average degree of polymerization 310) 100 parts by mass

Sugar ester compound 1 (shown in formula (S4)) 6.0 parts by mass

Sugar ester compound 2 (shown in formula (S5)) 2.0 parts by mass

Silica particle dispersion (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 0.1 parts by mass

Solvent (methylene chloride/methanol/butanol)

-------------------------------------------------- -----------

[Formula 5]

[Formula 6]

The dope prepared above was cast using a drum film forming machine. Dope was cast from a die so as to come into contact with the metal support cooled to 0°C, and then the obtained web (film) was peeled off. Moreover, the drum was made from SUS.

The web (film) obtained by casting was peeled off from the drum and dried for 20 minutes in a tenter apparatus at 30 to 40° C. during film conveyance using a tenter apparatus that clips both ends of the web with a clip and conveys it. Then, it post-dried by zone heating, carrying out roll conveyance of a web. After knurling was performed on the obtained web, it was wound up.

The film thickness of the obtained cellulose acylate film was 40 micrometers, and the in-plane retardation Re (550) in wavelength 550 nm was 1 nm and the thickness direction retardation Rth (550) in wavelength 550 nm was 26 nm.

(Formation of optically anisotropic layer)

The rubbing process was continuously performed on the cellulose acylate film produced above. At this time, the longitudinal direction of the elongated film and the conveying direction were parallel, and the angle formed by the longitudinal direction (conveying direction) of the film and the rotational axis of the rubbing roller was set to 80°. When the longitudinal direction (conveyance direction) of the film is set to 90° and the clockwise direction is indicated as a positive value with respect to the film width direction (0°) as observed from the film side, the rotation axis of the rubbing roller is at 10°. In other words, the position of the rotating shaft of the rubbing roller is a position rotated by 80 degrees counterclockwise with respect to the longitudinal direction of the film.

Using the rubbed long cellulose acylate film as a substrate, a composition for forming an optically anisotropic layer (1) containing a rod-shaped liquid crystal compound having the following composition was applied using a die coater to form a composition layer ( Corresponds to process 1A). In addition, the absolute value of the weighted average spiral induction force of the chiral agent in the composition layer in Step 1A was 0.0 μm ^-1 .

Next, the obtained composition layer was heated at 80°C for 60 seconds (corresponding to Step 2A). By this heating, the rod-shaped liquid crystal compound in the composition layer was oriented in a predetermined direction.

Thereafter, ultraviolet rays were irradiated to the composition layer for 5 seconds at 40° C. under oxygen-containing air (oxygen concentration: about 20% by volume) using a 365 nm LED lamp (manufactured by Acro Edge Co., Ltd.) (irradiation amount: 13 mJ). /cm ² ) (corresponds to process 3A).

Subsequently, the obtained composition layer was heated at 80°C for 10 seconds (corresponding to Step 4A).

Thereafter, nitrogen purging was performed, and the composition layer was irradiated with ultraviolet rays using a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) at 80° C. at an oxygen concentration of 100 ppm by volume (irradiation amount: 500 mJ/cm ² ), An optically anisotropic layer in which the alignment state of the liquid crystal compound was fixed was formed (corresponding to step 5A). In this way, an optical film (F-1) was produced.

The molar extinction coefficient at 365 nm of the left-twisting chiral agent (L1) in the composition for forming an optically anisotropic layer (1) is 40 L/(mol cm), and the HTP of this chiral agent is 365 nm. Even when light was irradiated (13 mJ/cm ² ), there was no change compared to before irradiation.

The molar extinction coefficient at 365 nm of the right-twisting chiral agent (R1) is 38,450 L/(mol cm), and the HTP of this chiral agent is, when irradiated with light of 365 nm (13 mJ/cm ² ), the same as before irradiation. In comparison, it decreased by 35 μm ^-1 .

The molar extinction coefficient at 365 nm of the photopolymerization initiator (Irgacure819) was 860 L/(mol cm).

-------------------------------------------------- -----------

Composition for Forming an Optically Anisotropic Layer (1)

-------------------------------------------------- -----------

The following rod-shaped liquid crystal compound (A) 80 parts by mass

The following rod-shaped liquid crystal compound (B) 10 parts by mass

The following polymerizable compound (C) 10 parts by mass

Ethylene oxide modified trimethylolpropane triacrylate

(V#360, manufactured by Osaka Yuki Kagaku Co., Ltd.) 4 parts by mass

Photopolymerization initiator (IRGACURE819, manufactured by BASF) 3 parts by mass

Left torsion chiralizer (L1) below 0.43 parts by mass

The right torsion chiralizer (R1) below 0.38 parts by mass

The following polymer (A) 0.08 parts by mass

Polymer (B) below 0.50 parts by mass

Methyl Isobutyl Ketone 116 mass parts

ethyl propionate 40 parts by mass

-------------------------------------------------- -----------

Rod-shaped liquid crystal compound (A) (hereinafter, a mixture of compounds)

[Formula 7]

rod-shaped liquid crystal compound (B)

[Formula 8]

Polymerizable compound (C)

[Formula 9]

Left torsion chiralizer (L1)

[Formula 10]

Right torsion chiralizer (R1)

[Formula 11]

Polymer (A) (In the formula, the numerical value described in each repeating unit represents the content (mass%) of each repeating unit with respect to all repeating units.)

[Formula 12]

Polymer (B) (In the formula, the numerical value described in each repeating unit represents the content (mass%) of each repeating unit with respect to all repeating units.)

[Formula 13]

The optical film (F-1) produced above was cut parallel to the rubbing direction, and the optically anisotropic layer was observed from the cross-sectional direction with a polarizing microscope. The thickness of the optically anisotropic layer is 2.7 μm, and the region (second region) having a thickness (d2) of 1.3 μm on the substrate side of the optically anisotropic layer is a homogeneous orientation without a torsion angle, and the air side of the optically anisotropic layer (opposite to the substrate) In the region (first region) having a thickness (d1) of 1.4 μm of the side), the liquid crystal compound was torsionally oriented.

In addition, the optical properties of the optical film (F-1) were obtained using Axometrics' Axoscan and the company's analysis software (Multi-Layer Analysis). The product (Δn2d1) of Δn2 and the thickness d2 at a wavelength of 550 nm in the second region is 173 nm, the twist angle of the liquid crystal compound is 0°, and the angle of the orientation axis of the liquid crystal compound with respect to the longitudinal direction of the film is that the side in contact with the substrate is -10°, the side contacting the first region was -10°.

In addition, the product (Δn1d1) of Δn1 and the thickness d1 at a wavelength of 550 nm in the first region is 184 nm, the twist angle of the liquid crystal compound is 75°, and the orientation axis angle of the liquid crystal compound with respect to the longitudinal direction of the film is The side in contact with was -10°, and the air side was -85°.

In addition, the orientation axis angle of the liquid crystal compound included in the optically anisotropic layer is negative when the film is observed from the surface side of the optically anisotropic layer with the longitudinal direction of the film as 0° as a reference, and clockwise (clockwise rotation) , the counterclockwise direction (left rotation) is expressed as a quantity.

In addition, the torsion structure of the liquid crystal compound here is determined by observing the substrate from the surface side of the optically anisotropic layer, and using the orientation direction of the liquid crystal compound on the surface side (front side) as a reference, the orientation direction of the liquid crystal compound on the substrate side (back side). Clockwise (right rotation) is negative, and counterclockwise (left rotation) is positive.

(Production of polarizer)

A polyvinyl alcohol (PVA) film having a thickness of 80 μm was immersed in an iodine aqueous solution having an iodine concentration of 0.05% by mass at 30° C. for 60 seconds and dyed. Next, while the obtained film was immersed in a boric acid solution having a boric acid concentration of 4% by mass for 60 seconds, it was longitudinally stretched to 5 times the original length, and then dried at 50°C for 4 minutes to obtain a polarizer having a thickness of 20 μm.

(Production of polarizer protective film)

A commercially available cellulose acylate film, FUJITAC TG40UL (manufactured by Fujifilm Co., Ltd.) was prepared, immersed in a 55°C sodium hydroxide aqueous solution at 1.5 mol/liter, and then the sodium hydroxide was thoroughly washed with water. Thereafter, the resulting film was immersed in a 35°C dilute sulfuric acid aqueous solution at 0.005 mol/liter for 1 minute, and then immersed in water to sufficiently wash the diluted sulfuric acid aqueous solution. Finally, the obtained film was sufficiently dried at 120°C, and a polarizer protective film having the surface subjected to saponification treatment was produced.

(Manufacture of circular polarizing plate)

In the same way as in the production of the polarizer protective film described above, the optical film (F-1) prepared above is subjected to saponification, and the above-described polarizer and the above-described polarizer protective film are applied to the substrate surface included in the optical film (F-1). were bonded together continuously using a polyvinyl alcohol-based adhesive to produce a long circular polarizing plate (P-1). That is, the circular polarizing plate (P-1) had a polarizer protective film, a polarizer, a substrate, and an optically anisotropic layer in this order.

In addition, the absorption axis of the polarizer coincides with the longitudinal direction of the circular polarizing plate, the rotation angle of the in-plane slow axis of the second region with respect to the absorption axis of the polarizer is 10°, and the second region side of the first region with respect to the absorption axis of the polarizer The rotation angle of the in-plane slow axis of the surface on the opposite side was 85°.

In addition, the rotation angle of the in-plane slow axis is expressed as a positive angular value in the counterclockwise direction and a negative angle value in the clockwise direction, by observing the optically anisotropic layer from the polarizer side and taking the longitudinal direction of the circular polarizing plate as 0 ° as a reference.

<Example 2>

(alkaline saponification treatment)

After passing the above-described cellulose acylate film through a dielectric heating roll at a temperature of 60 ° C. to raise the film surface temperature to 40 ° C., an alkali solution of the composition shown below is applied to the band surface of the film using a bar coater in an applied amount. It was applied at 14 ml/m ² and conveyed for 10 seconds under a steam type far-infrared heater made by Noritake Co., Ltd. heated to 110°C. Subsequently, 3 ml/m ² of pure water was applied using the same bar coater. Subsequently, after repeating water washing with a fountain coater and dehydration with an air knife three times, it was conveyed to a drying zone at 70°C for 10 seconds, dried, and an alkali saponified cellulose acylate film was produced.

-------------------------------------------------- -----------

alkaline solution

-------------------------------------------------- -----------

potassium hydroxide 4.7 parts by mass

water 15.8 parts by mass

isopropanol 63.7 mass parts

Surfactant: C ₁₄ H ₂₉ O (CH ₂ CH ₂ O) ₂₀ H 1.0 parts by mass

propylene glycol 14.8 parts by mass

-------------------------------------------------- -----------

(Formation of Alignment Film)

An alignment film coating solution having the following composition was continuously applied to the surface of the cellulose acylate film subjected to the alkali saponification treatment with a #14 wire bar. It dried for 60 seconds with warm air of 60°C and further for 120 seconds with warm air of 100°C.

-------------------------------------------------- -----------

Alignment film coating solution

-------------------------------------------------- -----------

Modified polyvinyl alcohol shown below 28 mass parts

Citric acid ester (AS3, manufactured by Sankyo Chemical Co., Ltd.) 1.2 parts by mass

Photopolymerization initiator (Irgacure2959, manufactured by BASF) 0.84 parts by mass

glutaraldehyde 2.8 parts by mass

water 699 mass parts

methanol 226 mass parts

-------------------------------------------------- -----------

(denatured polyvinyl alcohol)

[Formula 14]

(Formation of optically anisotropic layer)

Rubbing treatment was continuously performed on the alignment film prepared above. At this time, the longitudinal direction of the elongated film and the conveying direction were parallel, and the angle formed by the longitudinal direction (conveying direction) of the film and the rotational axis of the rubbing roller was set to 45°. When the longitudinal direction (conveyance direction) of the film is set to 90° and the clockwise direction is indicated as a positive value with respect to the film width direction (0°) as observed from the film side, the rotation axis of the rubbing roller is at 135°. In other words, the position of the rotating shaft of the rubbing roller is a position rotated by 45 degrees counterclockwise with respect to the longitudinal direction of the film.

Using the rubbed cellulose acylate film with an alignment film as a substrate, a composition for forming an optically anisotropic layer (2) containing a rod-shaped liquid crystal compound having the following composition was applied using a die coater to form a composition layer ( Corresponds to process 1C).

Next, the obtained composition layer was heated at 120°C for 80 seconds (corresponding to step 2C). By this heating, the rod-shaped liquid crystal compound in the composition layer was oriented in a predetermined direction.

Thereafter, the composition layer was irradiated with ultraviolet rays for 5 seconds at 40° C. under oxygen-containing air (oxygen concentration: about 20% by volume) using a 365 nm LED lamp (manufactured by Acro Edge Co., Ltd.) (irradiation amount: 30 mJ). /cm ² ) (corresponds to process 3C).

Subsequently, the obtained composition layer was heated at 90°C for 10 seconds (corresponding to Step 4C).

Thereafter, nitrogen purging was performed, and the composition layer was irradiated with ultraviolet rays using a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) at 55° C. at an oxygen concentration of 100 volume ppm (irradiation amount: 500 mJ/cm ² ), An optically anisotropic layer in which the alignment state of the liquid crystal compound was fixed was formed (corresponding to Step 5C). In this way, an optical film (F-2) was produced.

-------------------------------------------------- -----------

Composition for Forming an Optically Anisotropic Layer (2)

-------------------------------------------------- -----------

The above rod-like liquid crystal compound (A) 20 mass parts

The following rod-shaped liquid crystal compound (D) 40 parts by mass

The following rod-shaped liquid crystal compound (E) 40 parts by mass

Ethylene oxide modified trimethylolpropane triacrylate

(V#360, manufactured by Osaka Yuki Kagaku Co., Ltd.) 4 parts by mass

Photopolymerization initiator (IRGACURE819, manufactured by BASF) 3 parts by mass

Polymer (A) above 0.08 parts by mass

The following photosensitive compound (A) 0.4 parts by mass

The following ionic compound (A) 3.0 parts by mass

methyl ethyl ketone 156 mass parts

-------------------------------------------------- -----------

rod-shaped liquid crystal compound (D)

[Formula 15]

Rod-shaped liquid crystal compound (E)

[Formula 16]

photosensitive compound (A)

[Formula 17]

Ionic compounds (A)

[Formula 18]

Further, when the photosensitive compound (A) in the composition for forming an optically anisotropic layer (2) was irradiated with light of 365 nm (30 mJ/cm ² ), a hydrophilic carboxyl group-containing decomposition product (A) was generated.

Degradate (A)

[Formula 19]

The optical film (F-2) produced above was cut parallel to the rubbing direction, and the optically anisotropic layer was observed from the cross-sectional direction with a polarizing microscope. The thickness of the optically anisotropic layer is 4.3 μm, the 3.0 μm-thick region (second region) on the substrate side of the optical anisotropic layer is homogeneous, and the 1.3 μm-thick region on the air side (opposite to the substrate) of the optical anisotropic layer is In the region (first region), the liquid crystal compound was homeotropically aligned.

In addition, the optical properties of the optical film (F-2) were obtained using Axometrics' Axoscan and the company's analysis software (Multi-Layer Analysis). The in-plane retardation (Δn2d2) at a wavelength of 550 nm in the second region was 140 nm, and the angle of the in-plane slow axis with respect to the longitudinal direction of the film was -45°. In addition, the in-plane retardation (Δn1d1) in the first region at a wavelength of 550 nm was 0 nm, and the retardation in the thickness direction at a wavelength of 550 nm in the first region was -60 nm.

In addition, the angle of the in-plane slow axis is negative when observing the substrate from the surface side of the optically anisotropic layer with the longitudinal direction of the film as 0 ° as a reference, clockwise (clockwise rotation), counterclockwise (left rotation) Time is expressed as a quantity.

(Manufacture of circular polarizing plate)

In the same manner as in Example 1, the optical film (F-2) prepared above was subjected to saponification, and the above-described polarizer and the above-described polarizer protective film were coated with polyvinyl alcohol on the substrate surface included in the optical film (F-2). It was bonded together continuously using the system adhesive, and the circular polarizing plate (P-2) of the shape of a long picture was produced. That is, the circular polarizing plate (P-2) had a polarizer protective film, a polarizer, a substrate, and an optically anisotropic layer in this order.

Further, the absorption axis of the polarizer coincided with the longitudinal direction of the circular polarizing plate, and the rotation angle of the in-plane slow axis of the second region with respect to the absorption axis of the polarizer was 45°.

In addition, the rotation angle of the in-plane slow axis is expressed as a positive angular value in the counterclockwise direction and a negative angle value in the clockwise direction, by observing the optically anisotropic layer from the polarizer side and taking the longitudinal direction of the circular polarizing plate as 0 ° as a reference.

<Example 3>

(Formation of optically anisotropic layer)

The rubbing process was continuously performed on the cellulose acylate film produced in Example 1. At this time, the longitudinal direction of the elongated film and the conveyance direction were parallel, and the angle formed by the longitudinal direction (conveyance direction) of the film and the rotation axis of the rubbing roller was 45°. In addition, when the longitudinal direction (conveyance direction) of the film is set to 90 ° and observed from the cellulose acylate film side, and the counterclockwise direction relative to the width direction (0 °) of the cellulose acylate film is indicated as a positive value, the rubbing roller The axis of rotation was 135°. In other words, the position of the rotating shaft of the rubbing roller was a position rotated clockwise by 45° on the basis of the longitudinal direction of the cellulose acylate film.

Using the rubbed cellulose acylate film as a substrate, a composition layer for forming an optically anisotropic layer (3) containing a rod-shaped liquid crystal compound having the following composition was applied using a die coater to form a composition layer (step 1D corresponds to).

Next, the obtained composition layer was heated at 80°C for 60 seconds (corresponding to step 2D). By this heating, the rod-shaped liquid crystal compound in the composition layer was oriented in a predetermined direction.

Thereafter, ultraviolet rays were irradiated to the composition layer for 5 seconds at 40° C. under oxygen-containing air (oxygen concentration: about 20% by volume) using a 365 nm LED lamp (manufactured by Acro Edge Co., Ltd.) (irradiation amount: 50 mJ). /cm ² ) (for Process 3D).

Subsequently, the obtained composition layer was heated at 120°C for 10 seconds (corresponding to Step 4D). In addition, the phase transition temperature of the rod-shaped liquid crystal compound in the composition for forming an optically anisotropic layer (3) to the isotropic phase was 110°C.

Thereafter, nitrogen purging was performed, and the composition layer was irradiated with ultraviolet rays using a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) at 120° C. at an oxygen concentration of 100 volume ppm (irradiation amount: 500 mJ/cm ² ), An optically anisotropic layer in which the alignment state of the liquid crystal compound was fixed was formed (corresponding to step 5D). In this way, an optical film (F-3) was produced.

In addition, the molar extinction coefficient at 365 nm of the photoinitiator (Irgacure907) was 140 L/(mol·cm).

-------------------------------------------------- -----------

Composition for Forming an Optically Anisotropic Layer (3)

-------------------------------------------------- -----------

The above rod-like liquid crystal compound (A) 80 parts by mass

The above rod-like liquid crystal compound (B) 10 parts by mass

The above polymerizable compound (C) 10 parts by mass

Ethylene oxide modified trimethylolpropane triacrylate

(V#360, manufactured by Osaka Yuki Kagaku Co., Ltd.) 4 parts by mass

Photopolymerization initiator (Irgacure907, manufactured by BASF) 3 parts by mass

Polymer (A) above 0.08 parts by mass

Polymer (B) above 0.50 parts by mass

Methyl Isobutyl Ketone 116 mass parts

ethyl propionate 40 parts by mass

-------------------------------------------------- -----------

The optical film (F-3) produced above was cut parallel to the rubbing direction, and the optically anisotropic layer was observed from the cross-sectional direction with a polarizing microscope. The thickness of the optically anisotropic layer is 2.7 μm, the 1.1 μm-thick region (second region) on the substrate side of the optical anisotropic layer is homogeneous, and the 1.6 μm-thick region on the air side (opposite to the substrate) of the optical anisotropic layer is In the region (first region), the liquid crystal compound was in an isotropic state (isotropic phase).

In addition, the optical properties of the optical film (F-3) were obtained using Axoscan from Axometrics and the company's analysis software (Multi-Layer Analysis). The in-plane retardation (Δn2d2) at a wavelength of 550 nm in the second region was 140 nm, and the in-plane slow axis was -45°. In addition, the in-plane retardation (Δn1d1) in the first region at a wavelength of 550 nm was 0 nm, and the retardation in the thickness direction was 0 nm.

In addition, the angle of the in-plane slow axis is negative when observing the substrate from the surface side of the optically anisotropic layer with the longitudinal direction of the film as 0 ° as a reference, clockwise (clockwise rotation), counterclockwise (left rotation) Time is expressed as a quantity.

(Manufacture of circular polarizing plate)

In the same manner as in Example 1, the optical film (F-3) produced above was subjected to saponification, and the above-described polarizer and the above-described polarizer protective film were coated with polyvinyl alcohol on the substrate surface included in the optical film (F-3). It was bonded together continuously using the system adhesive, and the circular polarizing plate (P-3) of the shape of a long picture was produced. That is, the circular polarizing plate (P-3) had a polarizer protective film, a polarizer, a substrate, and an optically anisotropic layer in this order.

Further, the absorption axis of the polarizer coincided with the longitudinal direction of the circular polarizing plate, and the rotation angle of the in-plane slow axis of the second region with respect to the absorption axis of the polarizer was 45°.

In addition, the rotation angle of the in-plane slow axis is expressed as a positive angular value in the counterclockwise direction and a negative angle value in the clockwise direction, by observing the optically anisotropic layer from the polarizer side and taking the longitudinal direction of the circular polarizing plate as 0 ° as a reference.

<Example 4>

(Formation of optically anisotropic layer)

The rubbing process was continuously performed on the cellulose acylate film produced in Example 1. At this time, the longitudinal direction of the elongated film and the conveying direction were parallel, and the angle formed by the longitudinal direction (conveying direction) of the film and the rotating shaft of the rubbing roller was 90°.

Using the rubbed cellulose acylate film as a substrate, a composition layer for forming an optically anisotropic layer (4) containing a rod-shaped liquid crystal compound having the following composition was applied using a die coater to form a composition layer (step 1B). corresponds to). In addition, the absolute value of the weighted average spiral induction force of the chiral agent in the composition layer in Step 1B was 31 μm ^-1 .

Next, the obtained composition layer was heated at 100°C for 80 seconds (corresponding to Step 2B). By this heating, the rod-shaped liquid crystal compound in the composition layer was oriented in a predetermined direction.

Thereafter, ultraviolet rays were irradiated to the composition layer for 10 seconds at 40° C. under oxygen-containing air (oxygen concentration: about 20% by volume) using a 365 nm LED lamp (manufactured by Acroedge Co., Ltd.) (irradiation amount: 100 mJ). /cm ² ) (corresponds to process 3B).

Subsequently, the obtained composition layer was heated at 90°C for 10 seconds (corresponding to step 4B).

Thereafter, nitrogen purging was performed, and the composition layer was irradiated with ultraviolet rays using a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) at 55° C. at an oxygen concentration of 100 volume ppm (irradiation amount: 500 mJ/cm ² ), An optically anisotropic layer in which the alignment state of the liquid crystal compound was fixed was formed (corresponding to Step 5B). In this way, an optical film (F-4) was produced.

In addition, the molar extinction coefficient at 365 nm of the sensitizer (Kayacure DETX) was 4200 L/(mol cm).

-------------------------------------------------- -----------

Composition for Forming an Optically Anisotropic Layer (4)

-------------------------------------------------- -----------

The above rod-like liquid crystal compound (A) 80 parts by mass

The above rod-like liquid crystal compound (B) 10 parts by mass

The above rod-like liquid crystal compound (C) 10 parts by mass

Ethylene oxide modified trimethylolpropane triacrylate

(V#360, manufactured by Osaka Yuki Kagaku Co., Ltd.) 4 parts by mass

Photopolymerization initiator (Irgacure907, manufactured by BASF) 3 parts by mass

Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 1 part by mass

The above right-twist chiral agent (R1) 11 mass parts

Polymer (A) above 0.08 parts by mass

Polymer (B) above 0.5 parts by mass

Methyl Isobutyl Ketone 117 mass parts

ethyl propionate 39 mass parts

-------------------------------------------------- -----------

The optical film (F-4) produced above was cut parallel to the rubbing direction, and the optically anisotropic layer was observed from the cross-sectional direction by SEM. The thickness of the optically anisotropic layer is 3.6 μm, and a region (second region) on the substrate side of the optically anisotropic layer having a thickness of 1.8 μm and a region (second region) having a thickness of 1.8 μm on the air side (opposite to the substrate) of the optically anisotropic layer (first region). region), and the second region and the first region each had a cholesteric orientation with different helical pitches.

Further, the spectral reflection characteristics of the optical film (F-4) were determined using an integrated reflectance meter. It was confirmed that the film was a two-band cholesteric liquid crystal film having a reflection band centered at 450 nm derived from the second region and a reflection band centered at 650 nm derived from the first region.

<Comparative Example 1>

In Example 1 described above, except that the irradiation with the 365 nm LED lamp was conducted under a nitrogen purge (oxygen concentration: 100 ppm by volume) instead of under oxygen-containing air (oxygen concentration: about 20 vol%). , According to the same procedure as in Example 1, the optical film (C-1) was produced in the same manner as in the production method of the optical film (F-1). That is, in Comparative Example 1, Step 3A was not performed.

In addition, as a result of observing the cross section of the optically anisotropic layer in the same procedure as in Example 1, homogeneous orientation was formed over the entire thickness direction of the obtained optically anisotropic layer, and the desired effect of the present invention was not obtained.

<Comparative Example 2>

In the above-described Example 1, after irradiation with a 365 nm LED lamp at 40 ° C., the optical film (F Optical film (C-2) was produced in the same manner as in the production method of -1). That is, in Comparative Example 2, Step 4A was not performed.

In addition, as a result of observing the cross section of the optically anisotropic layer in the same procedure as in Example 1, homogeneous orientation was formed over the entire thickness direction of the obtained optically anisotropic layer, and the desired effect of the present invention was not obtained.

<Comparative Example 3>

In the above-described Example 1, the manufacturing method of the optical film (F-1) except that the irradiation conditions in step 3A were changed to irradiation with a 365 nm LED lamp for 100 seconds (irradiation amount: 13 mJ/cm ² ). In the same manner as above, an optical film (C-3) was produced. That is, in Comparative Example 3, compared with Example 1, the irradiation amount was the same, but the irradiation time was lengthened.

In addition, as a result of observing the cross section of the optically anisotropic layer in the same procedure as in Example 1, torsion orientation was formed over the entire thickness direction of the optically anisotropic layer obtained, and the desired effect of the present invention was not obtained.

The in-plane retardation Re(λ) at the wavelength λ of the optically anisotropic layer thus produced was measured by Axoscan manufactured by Axometrics. The results are shown in Table 1.

<Production of organic EL display device and evaluation of display performance>

(Mounting to display device)

GALAXY S4 manufactured by SAMSUNG equipped with an organic EL panel is disassembled, the circular polarizing plate is peeled off, and the circular polarizing plates (P-1) to (P-3) produced in the above examples are placed outside the polarizer protective film. It was bonded to the display device as much as possible.

(Evaluation of display performance)

(Front direction)

Black display was applied to the produced organic EL display device, and it was observed from the front direction under bright light, and color change was evaluated according to the following criteria. The results are shown in Table 1.

4: Color change is not recognized at all. (permit)

3: Color change is slightly recognized, but slightly. (permit)

2: A color change is recognized, but the reflected light is small, and there is no problem in use. (permit)

1: Color change is recognized, and reflected light is large, which is not acceptable.

(oblique direction)

Black display was applied to the produced organic EL display device, and a fluorescent lamp was illuminated from a polar angle of 45° under bright light, and reflected light was observed from all directions. The azimuth dependence of color change was evaluated according to the following criteria. The results are shown in Table 1.

4: Color tone difference is not visually recognized at all. (permit)

3: Color tone difference is recognized, but very slightly. (permit)

2: Although color tone difference is visually recognized, reflected light is small and there is no problem in use. (permit)

1: A difference in color tone is visually recognized, and the reflected light is also large, which is not acceptable.

In Table 1, "in-plane retardation" shows the in-plane retardation in each wavelength of an optically anisotropic layer.

[Table 1]

As shown in Table 1, it was confirmed that the retardation of the optically anisotropic layer in each example exhibited reverse wavelength dispersion, and color change and reflection were suppressed when this optically anisotropic layer was used in an organic EL display device.

<Production of liquid crystal display device and evaluation of display performance>

(Manufacture of circular polarizing plate)

The optical film (F-1) prepared above is subjected to saponification, and the above-described polarizer and the above-described polarizer protective film are bonded to the substrate surface included in the optical film (F-1) using a polyvinyl alcohol-based adhesive, , and produced a circularly polarizing plate (P-4). At this time, it bonded so that the angle which the absorption axis of a polarizer and the longitudinal direction of an optical film (F-1) make might become 90 degrees. That is, the rotation angle of the in-plane slow axis of the second region with respect to the absorption axis of the polarizer is 100°, and the rotation angle of the in-plane slow axis of the surface opposite to the second region side of the first region with respect to the absorption axis of the polarizer is 175 degrees. was °

In addition, the rotation angle of the in-plane slow axis is expressed as a positive angle in the counterclockwise direction and a negative angle value in the clockwise direction by observing the optically anisotropic layer from the side of the polarizer and taking the direction of the absorption axis of the polarizer as 0 ° as a reference.

(Production of liquid crystal display device 1)

In the following manner, transflective liquid crystal display device 1 in VA mode was produced. The orientation film of the liquid crystal cell used polyimide, and the cell gap of the transmissive part was 4.0 µm, and the cell gap of the reflective part was 2.0 µm. A nematic liquid crystal having a negative dielectric anisotropy was injected into the attack portion. When no voltage was applied to the upper and lower substrates of this liquid crystal cell, the nematic liquid crystals were vertically aligned. In addition, when a voltage was applied, protrusions were formed on the cell substrate so that the nematic liquid crystals were inclined in two directions, the directions of which differed by 180 degrees. In-plane retardation at a wavelength of 550 nm when a voltage is applied to this liquid crystal cell for white display, the transmission portion is 280 nm and the reflection portion is 140 nm, and the in-plane retardation at a wavelength of 550 nm when displaying black without application is, The transmission portion was 0 nm, and the reflection portion was 0 nm.

A transflective type liquid crystal display device 1 was produced by attaching the circular polarizing plate (P-1) and the circular polarizing plate (P-4) prepared above to a liquid crystal cell composed of the upper and lower substrates and a liquid crystal layer sandwiched between the substrates. At this time, the circular polarizing plate (P-1), the liquid crystal cell, the circular polarizing plate (P-4), and the backlight were arranged in this order from the side of the observer. In the circular polarizing plate (P-1), the polarizer and the optical film (F-1) are in this order from the observer side, and the circular polarizing plate (P-4) is the optical film (F-1) from the observer side. And the polarizers were arranged in this order so that the angle formed by the absorption axis of each polarizer included in the circular polarizing plate (P-1) and the circular polarizing plate (P-4) was 90°. Further, when the nematic liquid crystal held by the upper and lower substrates was tilted, the rotation angle of the long axis of the nematic liquid crystal in the direction (in-plane slow axis) projected onto the cell substrate was 45°.

In addition, the angle of rotation of the projected direction (in-plane slow axis) is positive in the counterclockwise direction by observing the liquid crystal cell from the side of the circular polarizing plate (P-1) and setting the direction of the absorption axis of the polarizer as 0 ° as a reference. It is indicated with a negative angle value in a clockwise direction.

(Manufacture of circular polarizing plate)

In the same manner as in Example 1 or Example 25 of Japanese Patent Publication No. 6770649, an alignment film was formed on the cellulose acylate film, and further, an optically anisotropic layer H made of a discotic liquid crystal compound or a rod-shaped liquid crystal was formed thereon. An optically anisotropic layer Q made of the compound was produced. At this time, the thickness of the coating layer and the rubbing angle were adjusted so as to become the following retardation and slow axis angle. The in-plane retardation of the optically anisotropic layer H at a wavelength of 550 nm was 280 nm, and the in-plane retardation of the optically anisotropic layer Q at a wavelength of 550 nm was 120 nm.

Then, the optically anisotropic layer Q, the optically anisotropic layer H, the above-mentioned polarizer, and the above-mentioned polarizer protective film were bonded together using an adhesive so as to be in this order, and a circular polarizing plate (P-5) was produced. At this time, the cellulose acylate film and the alignment film were separated from the optically anisotropic layer H and the optically anisotropic layer Q, so that they were not included in the circular polarizing plate. In addition, the rotation angle of the in-plane slow axis of the optical anisotropic layer H with respect to the absorption axis of the polarizer is -75 °, and the rotation angle of the in-plane slow axis of the optically anisotropic layer Q with respect to the absorption axis of the polarizer is -15 °.

In addition, the rotation angle of the in-plane slow axis is expressed as a positive angle in the counterclockwise direction and a negative angle value in the clockwise direction by observing the optically anisotropic layer from the side of the polarizer and taking the direction of the absorption axis of the polarizer as 0 ° as a reference.

(Production of liquid crystal display device 2)

In the following manner, transflective liquid crystal display device 2 in ECB mode was produced. The orientation film of the liquid crystal cell was made of polyimide, and the rubbing direction was made to be parallel up and down. The cell gap of the transmissive portion was 4.0 μm, and the cell gap of the reflective portion was 2.0 μm. A nematic liquid crystal having a positive dielectric anisotropy was injected into the attack portion. The in-plane retardation at a wavelength of 550 nm when a voltage is applied to this liquid crystal cell is: 280 nm for the transmittance during white display, 140 nm for the reflector for white display, 40 nm for the transmittance for black display, and 20 nm for the reflector for black display. was Also, when the nematic liquid crystal held by the upper and lower substrates was tilted by voltage application, the direction in which the long axis of the nematic liquid crystal was projected onto the cell substrate (in-plane slow axis) coincided with the rubbing direction.

A transflective liquid crystal display device 2 was produced by attaching the circular polarizing plate (P-1) and the circular polarizing plate (P-5) prepared above to a liquid crystal cell composed of the upper and lower substrates and a liquid crystal layer sandwiched between the substrates. At this time, a circular polarizing plate (P-5), a liquid crystal cell, a circular polarizing plate (P-1), and a backlight were disposed in this order from the side of the observer. Further, in the circular polarizing plate (P-5), the polarizer, the optically anisotropic layer H, and the optically anisotropic layer Q are in this order from the side of the observer, and the circular polarizing plate (P-1) is, from the side of the observer, the optical film (F- 1) and the polarizer were arranged in this order. In addition, the angle formed by the absorption axis of each polarizer included in the circular polarizing plate (P-5) and the circular polarizing plate (P-1) is 90 °, and the rubbing direction applied to the alignment film of the liquid crystal cell and the circular polarizing plate (P-1) The angle formed by the in-plane slow axis direction of the optically anisotropic layer Q included in 5) was arranged to be 0°.

(Evaluation of display performance)

Applied voltages were adjusted for the transmissive portion and the reflecting portion of the VA mode transflective liquid crystal display device 1 and the ECB mode liquid crystal display device 2 prepared above, and black display and white display visibility were visually evaluated. In any display device, it was confirmed that good white/black contrast was exhibited, and the optically anisotropic layer of this example could be suitably used for a liquid crystal display device.

<Example 5>

(Formation of optically anisotropic layer)

Rubbing treatment was continuously performed on the alignment film prepared in Example 2. At this time, the longitudinal direction of the elongated film and the conveyance direction were parallel, and the angle formed by the longitudinal direction (conveyance direction) of the film and the rotational axis of the rubbing roller was set to 90°.

Using the rubbed cellulose acylate film with an alignment film as a substrate, a composition for forming an optically anisotropic layer (5) containing a rod-shaped liquid crystal compound having the following composition was applied using a die coater to form a composition layer ( Corresponds to process 1C).

Next, the obtained composition layer was heated at 120°C for 80 seconds (corresponding to Step 2C). By this heating, the rod-shaped liquid crystal compound in the composition layer was oriented in a predetermined direction.

Thereafter, the composition layer was irradiated with ultraviolet rays for 5 seconds at 40° C. under oxygen-containing air (oxygen concentration: about 20% by volume) using a 365 nm LED lamp (manufactured by Acro Edge Co., Ltd.) (irradiation amount: 30 mJ). /cm ² ) (corresponds to process 3C).

Subsequently, the obtained composition layer was heated at 90°C for 10 seconds (corresponding to Step 4C).

Thereafter, nitrogen purging was performed, and the composition layer was irradiated with ultraviolet rays using a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) at 55° C. at an oxygen concentration of 100 volume ppm (irradiation amount: 500 mJ/cm ² ), An optically anisotropic layer in which the alignment state of the liquid crystal compound was fixed was formed (corresponding to Step 5C). In this way, an optical film (F-5) was produced.

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Composition for Forming an Optically Anisotropic Layer (5)

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The following rod-shaped liquid crystal compound (F) 42 mass parts

The following rod-shaped liquid crystal compound (G) 42 mass parts

The following rod-shaped liquid crystal compound (H) 12 mass parts

The following rod-shaped liquid crystal compound (I) 4 parts by mass

NK Ester A-200 (manufactured by Shin Nakamura Chemical Co., Ltd.) 1 part by mass

HiSolve MTEM (Toho Kagaku High School) 2 parts by mass

Photopolymerization initiator (IRGACURE819, manufactured by BASF) 3 parts by mass

Polymer (A) above 0.08 parts by mass

The above photosensitive compound (A) 0.4 parts by mass

The above ionic compound (A) 3.0 parts by mass

methyl ethyl ketone 156 mass parts

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Rod-shaped liquid crystal compound (F)

[Formula 20]

Rod-shaped liquid crystal compound (G)

[Formula 21]

Rod-shaped liquid crystal compound (H)

[Formula 22]

rod-shaped liquid crystal compound (I)

[Formula 23]

The optical film (F-5) produced above was cut parallel to the rubbing direction, and the optically anisotropic layer was observed from the cross-sectional direction with a polarizing microscope. The thickness of the optical anisotropic layer is 4.3 μm, the region (second region) with a thickness of 2.4 μm on the substrate side of the optical anisotropic layer is homogeneous orientation, and the thickness of 1.9 μm on the air side (opposite to the substrate) of the optical anisotropic layer is In the region (first region), the liquid crystal compound was homeotropically aligned.

Further, the optical properties of the optical film (F-5) were obtained using Axometrics' Axoscan and the company's analysis software (Multi-Layer Analysis). The in-plane retardation (Δn2d2) at a wavelength of 550 nm in the second region was 130 nm, and the angle of the in-plane slow axis with respect to the longitudinal direction of the film was 0°. In addition, the in-plane retardation (Δn1d1) in the first region at a wavelength of 550 nm was 0 nm, and the retardation in the thickness direction at a wavelength of 550 nm in the first region was -100 nm.

In addition, the angle of the in-plane slow axis is 0° relative to the longitudinal direction of the film.

(Manufacture of optical compensation plate of liquid crystal display device)

The optical film (F-5) produced above is saponified, and the above-described polarizer and the above-described polarizer protective film are continuously applied to the surface of the optically anisotropic layer included in the optical film (F-5) using a polyvinyl alcohol-based adhesive. , and a long polarizing plate (P-6) was produced. That is, the polarizing plate (P-6) had a polarizer protective film, a polarizer, an optically anisotropic layer, and a substrate in this order.

In addition, the absorption axis of the polarizer coincided with the longitudinal direction of the polarizer, and the rotation angle of the in-plane slow axis of the second region with respect to the absorption axis of the polarizer was 0°.

In addition, the angle of rotation of the in-plane slow axis is determined by observing the optically anisotropic layer from the polarizer side, and taking the longitudinal direction of the polarizing plate as 0° as a reference.

(Production of liquid crystal display device 3)

A commercially available liquid crystal display device (iPad (registered trademark), manufactured by Apple) (a liquid crystal display device including a liquid crystal cell in FFS mode) is peeled off on the surface side, and the prepared polarizing plate (P-6) is optically removed. Liquid crystal display device 3 was produced by bonding with a 20 μm acrylic adhesive so that the film side was disposed on the liquid crystal cell side and the absorption axis of the polarizer was orthogonal to the absorption axis of the polarizer in the polarizing plate on the backlight side.

(Evaluation of display performance)

Regarding the produced liquid crystal display device 3, the visibility in the oblique direction of black display and white display was visually evaluated by adjusting the applied voltage. Liquid crystal display device 3 exhibited good white/black contrast, and it was confirmed that the optically anisotropic layer of this example can be suitably used for an optical compensation plate of a liquid crystal display device.

10 substrate
12, 120, 220, 320, 420 composition layer
12A, 120A, 220A, 320A, 420A lower region
12B, 120B, 220B, 320B, 420B upper region
20 optically anisotropic layer
22 different optically anisotropic layers
24 laminate
26 polarizer
28 Optically anisotropic layer with polarizer

Claims (8)

Step 1 of forming a composition layer containing a liquid crystal compound having a polymerizable group;
Step 2 of subjecting the composition layer to heat treatment to orient the liquid crystal compound in the composition layer;
After Step 2, Step 3 of irradiating the composition layer with light for 50 seconds or less and at 300 mJ/cm ² or less under conditions of an oxygen concentration of 1% by volume or more;
Step 4 of subjecting the composition layer to heat treatment at a temperature higher than that at the time of light irradiation after Step 3;
After the step 4, the composition layer is cured, and an optically anisotropic layer having a plurality of regions having different orientation states of the liquid crystal compound along the thickness direction is formed. The method of claim 1,
The composition layer comprises a photosensitive material selected from the group consisting of a photopolymerization initiator and a photosensitizer,
The method for producing an optically anisotropic layer, wherein the molar extinction coefficient of the photosensitive material at the wavelength of light irradiation in step 3 is 5000 L/(mol cm) or less. According to claim 1 or claim 2,
The composition layer contains a chiral agent,
The method for producing an optically anisotropic layer, wherein the chiral agent includes a photosensitive chiral agent whose helical organic force changes upon light irradiation. The method of claim 3,
The manufacturing method of the optically anisotropic layer, wherein the total content of the chiral agents relative to the total mass of the liquid crystal compound is 5.0% by mass or less. The method of claim 3,
The manufacturing method of the optically anisotropic layer, wherein the total content of the chiral agents with respect to the total mass of the liquid crystal compound is more than 5.0% by mass. According to claim 1 or claim 2,
The method for producing an optically anisotropic layer, wherein the composition layer comprises a photosensitive compound whose polarity changes upon irradiation with light. The method of claim 6,
The method for producing an optically anisotropic layer, wherein the photosensitive compound is a photosensitive compound that becomes hydrophilic by light irradiation. According to claim 1 or claim 2,
The manufacturing method of the optically anisotropic layer, wherein the temperature of the heat treatment in step 4 is equal to or higher than the temperature at which the liquid crystal compound becomes isotropic.

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